Chapter 13

OVERVIEW OF CONVENTIONAL AND NOVEL DEVICES

The devices which we have discussed so far in this book have been chosen based on the fact that they presently have been demonstrated to have useful microwave performance. Except for two very recent devices - the RTD and the HBT - they are being employed in numerous system applications, and the latter two devices are likely to find practical use in the near future as well. There are quite a large number of additional devices which have been proposed, and are being researched actively. It appears impossible to give justice to a treatment of all such "novel" devices, without doubling the size of this book. Fortunately, a couple of other recent books devote themselves entirely to this topic (Capasso, 1990; Sze, 1990). Of course, further devices will also be proposed in the future. A common occurrence is actually that a device may have been proposed long before it was feasible to realize it - a good example is the HBT, which was proposed in 1953, but had to await the development of crucial technology before it became realizable in the 1980s, as discussed in Chapter 12. The key elements which have to be present before a device is realized are:

(1) an understanding of the relevant basic solid state physics;

(2) the fabrication technology;

(3) the idea for the device;

The device usually will not be realized until the first two items are at a sufficient state of development, although item (1) sometimes occurs after the operation of the device, as it did in the case of the GUNN device (Chapter 2). The device may also evolve gradually, while the state of knowledge in the above three areas expands. A good example is the HFET (Chapter 11), where the first advances primarily served to clarify important physical phenomena occurring in quantum wells, formed in heterostructures made from semiconductors of different bandgaps. This soon led to the discovery of unprecedentedly high mobilities, and other physical phenomena related to the 2DEG, such as the quantum Hall effect, the discovery of which was awarded the Nobel prize in physics. In terms of device performance, however, the high mobility turned out to play only a minor role. As discussed in Chapter 11, it took many years of research after the first HFET device was realized, before this was understood. We believe that it is very instructive to study the way devices have evolved over time, and let the insights gained from this study guide the research on the new devices.

S. Yngvesson, Microwave Semiconductor Devices© Kluwer Academic Publishers 1991

450 Microwave Semiconductor Devices

There are some important conclusions we can draw from the development so far of microwave solid state devices. One conclusion is that we need to vigorously pursue all the three above-mentioned directions of effort in parallel. The actual stage of development at which all the required factors are present which make a device idea "ripe", still appears to be hard to predict (note Kroemer's prediction, however, quoted at the beginning of the section on HBTs in Chapter 12!). Another conclusion is that the main physical phenomena, which we have studied in relation to the devices chosen for this book, also tend to be the ones which are useful for the understanding of most "novel" devices presently being investigated. In that sense, this book will hopefully have a lasting value, even considering the high rate at which new ideas succeed each other in present microwave device research. We will also be able to draw on the material we have discussed in order to offer a brief review below of some other novel devices. This review clearly cannot be complete, but is intended to illustrate some of the diversity of these device ideas.

HOT ELECTRON TRANSISTORS

It should be clear that the electrons in essentially all devices discussed in this book become "hot electrons", at least in a section of the device. In a class of devices called hot electron transistors one attempts to inject hot electrons directly into the controlling region of the device (the "base") and then collect these in a collector, while keeping the dimensions so small that the hot electrons essentially will transit in the ballistic mode, i.e. they will not be scattered at all in the base region. Not surprisingly, the hot electron transistor was also proposed a long time ago (Mead, 1960). We discussed a generic device of this type in Chapter 10, and pointed out the large increase in device speed which would follow from the high average velocity of the ballistic electrons. The requirement is of course that the base length (L) be less than a mean free path (mfp). The electrons might be pictured as consisting of two groups: ballistic and "quasi-ballistic" electrons, where the latter group would be the electrons which had suffered a small number of scattering events. The fraction of the total number of electrons which are in the ballistic group is called etB and is given by the following expression, for the case where L « mfp (Heiblum and Fischetti, 1990):

1 etB = 1--­

mfp (13.1)

The injection of the electrons can occur thermionically by using a potential barrier. In an alternative device, the Tunneling Electron Hot Electron Ampli­fier (TH ETA), the injection is due to tunneling (Heiblum, 1980). A typical energy band diagram is shown in Figure 13.1. The tunneling barrier to the left in this figure consists of AIGaAs with z = 0.28. The base is In.12Ga.88As. The collector is also fabricated from AIGaAs (with a short graded transition region) in order to stop low energy electrons in the base from leaking out to the collector, followed by an InGaAs section. In recent devices, etB as high as

Chapter 13

Electron Energy

Injector J Ec~q1

GaAs Emitter

eVBE

L~~ AIGaA.

10nm

InGaAs Base

AIGaA. InGaAs Collector

451

Figure IS.1. Schematic diagram of the conduction band of a THETA de­vice under forward-bia, operation. Reprinted from SED, K., HEIBL UM, M., KNOEDLER, C.M., OH, J.E., PAMULAPATI, J., and BATTACHARYA, P. (1989). "High-Gain Pseudomorphic InGaAs Base Ballistic Hot-Electron Device," IEEE Electron Device Lett., EDL- 10, 73, @1989 IEEE.

0.7 has been measured, with a common base current gain Ct (see Chapter 12) of 0.97 (Seo et al., 1989).

The T H ETA and other similar devices have produced very interesting information regarding hot electrons. By varying the collector-base voltage, one can perform "spectroscopy" experiments on the electrons, i.e. determine the distribution function versus energy. Based on such experiments, Heiblum and Fischetti (1990) state that the dominant scattering mechanism for hot electrons under these conditions (the base is highly doped, and very short) is inelastic scattering in which the electrons lose a substantial amount of energy, and thus thermalize. This is in distinction to the prevailing idea, which we discussed in Chapter 10, that the scattering is primarily inelastic, with small scattering angles dominant. An unsolved aspect of the theoretical treatment of the scattering of electrons in a hot-electron device, is the fact that the base is so thin that the electrons should be regarded as existing in discrete states, similar to those in RTD devices and in the channel of HFETs. These states give rise to oscillations in the Ic/VBE characteristic (Seo et al., 1989). A related problem is the quantum-mechanical reflection of electrons by the collector-base barrier, even when the electrons have sufficient energy to pass the barrier! The type of experiments represented by the T H ETA device clearly will be very useful in the future for developing more detailed models for all high-speed devices.

Can the hot-electron type of device become a practical microwave device? The first requirement to fulfill is to realize a low base resistance to the very short base, a problem similar to that of the HBT, discussed in Chapter 12. One method for this is to utilize an "induced base", which results in a low

452 Microwave Semiconductor Devicell

base resistance, without requiring high base doping (Luryi, 1985; Chang et al., 1986). The induced base transistor (IBT) employs a base which may be only 100 A in length - a quantum well - which is populated by electrons due to a large positive collector voltage, see Figure 13.2. Thus no doping is needed in either the base or the collector. In actual devices, two depleted charge sheets are grown into the base to shape the potential barrier. The quantum well is separated from these by an undoped spacer layer, in analogy to the design of RFETs. The base resistance becomes very low due to the high mobility of the 2DEG electrons in the quantum well parallel to the potential barriers, especially at low temperatures (the effect which was originally believed to make RFETs very fast!). A base resistance of 100 ohms/ square is feasible. A value of310 ohms/ square was measured by (Chang et al., 1986), as well as a = 0.96. In terms of device speed, we note that the transit time through a 300 A base would be 30 fsec, and about 250 fsec for the collector. The device speed will clearly not be dominated by these, but by other charging times, as discussed for RBTs in Chapter 12. It appears possible to realize a total T = 0.5 psec (Reiblum and Fischetti, 1990), or IT = 300 GRz. It may be interesting to note that the IBT combines features which we are familiar with from the HFET, the RBT, and MISFETs (or MOSFETs, which also utilize inversion layers). RBTs are now also being developed with "ballistic injectors". Yet a different configuration is represented by the Bipolar Inversion Channel FET (BICFET) (Taylor and Simmons, 1985). This device also employs an inversion channel, but with thermionic emission from the emitter, and a resulting high common emitter gain (13) of 900 (Kiely et al., 1989) for an n-channel device in the I nGaAB / I nAIAB / I nGaAB system. The present device suffers from a decrease of 13 with increasing current density, which will require further development. The ratio of the transconductance to the input capacitance is predicted to be large for the BICFET, resulting in a small time-constant TE (see Chapter 12). If the base resistance can be made very small, and if high 13s can be sustained at high current density, then the BICFET should compete with the other high-speed devices we have discussed. No microwave data are presently available.

The number of possible configurations of hot-electron transistors is large, and it would be surprising if one or more devices of interest for microwave engineering were not to result from work in this area.

RESONANT TUNNELING TRANSISTORS

Several transistor configurations have been investigated, which make use of resonant tunneling through a double barrier, of the type described in Chapter 4. For example, the general concept was described by Davis and Hosack (1963) and Iogansen (1964). Later, Capasso and Kiehl (1985) proposed a Resonant Tunneling Bipolar Transistor (RTBT), with a resonant tunneling structure in the emitter. Other versions would use this type of structure in the base. Changing the base-emitter voltage lines up the energy of the emitted electrons

Chapter 13 453

Vee

Figure 13.2. Schematic conduction band diagram of an induced base tran­sistor with a positive bias applied to the collector. Reprinted from CHANG, C.Y., LIU, W.C., JAME, M.S., WANG, Y.H., LURYI, S., and SZE, S.M. (1986). "Induced Base Transistor Fabricated by Molecular Beam Epitazy," IEEE Electron Device Lett., EDL-7, -197, @1986 IEEE.

with the resonant state in the well, and thereby controls the current to the collector. It is then possible to obtain a tunable negative resistance, and a negative transconductance. In a Resonant Tunneling Hot Electron Transistor (RHET), electrons are injected through a double barrier into a structure similar to that of the hot electron transistor. An InGaAs-based RHET achieved a common emitter current gain ca) of 17, and a peak-to-valley ratio of 19.3 (Yokoyama et aI., 1990). Alternatively to a double-barrier, one may use a super-lattice, which consists of many periods of barriers and wells.

Microwave cut-off frequencies (IT) of about 24 GHz have been measured for both the RHET and the RTBT. The main unique characteristic of this type of device is probably the feasibility to tailor the loY-characteristic, how­ever. Lunardi et aI. (1989) developed an RTBT lattice-matched to InP, which has two cascaded double-barrier structures in the emitter. Both the output (Ie /VeE ) and the transfer (Ie /VBE ) characteristics exhibit two peaks, with large peak-to-valley ratios, see Figure 13.3. This characteristic favors the pro­duction of the fifth harmonic, as was demonstrated by Lunardi et al. (1989). Compared with a cascade of RTD diodes, the RTBT has the advantage of a higher power level.

454

<{

E

u H

Microwave Semiconductor Devices

VCE = 3_2 V

o L-~~~L-~~~ __ ~-L~--J

o

Figure 13.3. Transfer characteristic of a multiple-state RTBT in the com­mon emitter configuration. Reprinted from L UNARDI, L.M., SEN, S., CA­PASSO, F., SMITH, P.R., SIVCO, D.L., and CHO, A. Y. (1989). "Mi­crowave Multiple-State Resonant- Tunneling Bipolar Transistors," IEEE Elec­tron Device Lett., EDL-10, 219, @1989 IEEE.

PERMEABLE BASE TRANSISTORS

The permeable base transistor has a structure which is a semiconductor equivalent of the vacuum triode (Bozier et al., 1979), see Figure 13.4. It is a vertical device, which still functions more like a FET than a BJT. The emitter is an ohmic contact to n+ GaAs, on which an epitaxial layer is grown. A thin (300-500 A) metallic tungsten grating (the base) is grown directly on this layer. The high conductivity of the metal guarantees a low base resistance (5-10 ohms/ square). Finally, the base is overgrown with GaAs to form the collector, using OMCVD. The grating forms a Schottky barrier with the GaAs, which creates a depletion region, controllable by the base voltage. At a certain voltage, channels form between the gate fingers. A vertical section of the device stretching from the middle of a base finger to the center of the channel is equivalent to a MESFET, and the entire device thus consists of a large number of parallel MESFETs. The PBT shares with the HBT a compact geometry, which diminishes phasing problems between different sections of the device. For example, a device with a total base periphery of 1 mm had an active area of 8 x 20~m2 (Actis et al., 1987). The PBT also has very low leakage and a small feedback capacitance. The first property leads to a high output resistance, and both features contribute to a high device gain.

The technological hurdles which have been overcome in the fabrication of PBTs are quite different from those encountered with other devices. The major

Chapter 13

TUNGSTEN GRATING 0.32-fLm PER 100 n

455

COLLECTOR CONTACT

EMITTER CONTACT

Figure 13.4. Cross-section 01 a permeable base transistor. Reprinted from BOZLER, C.O., ALLEY, G.D., MURPHY, R.A., FLANDERS, D.C., and LINDLEY, W.T. (1979). "Premeable Base Transistor," Proc. 7th Bien. IEEE/ Cornell ConI. Active Microw. Semicond. Devices, Ithaca, NY, @1979 IEEE.

initial difficulty had to do with contamination of the GaAs from impurities in the tungsten grating. These problems have largely been solved, and PBT devices with a grating period of .24 p,m have been fabricated which yield 7.5 dB of gain as high as 94 GHz (Hollis and Murphy, 1990), and extrapolated imQ2 of about 265 GHz, assuming a 6 dB/octave roll-off. The frequency response of transistors at millimeter wave frequencies is likely to be more complicated than the one-pole response which yields the 6 dB/octave roll-off, however, as shown by, for example, Steer and Trew (1986), and Prasad et a1. (1988). The iT-value for the PBT device was only 38 GHz, and we can expect high values of the imQ2 / iT ratio due to the very low base resistance. Monte Carlo simulation predicts IT of 65 GHz for devices with a slightly different doping profile (Hwang et al., 1987). PAE of 53% with 75 mW output power and 30% with 500 mW output power, have been measured close to 22 GHz (Hollis and Murphy, 1990). A typical break-down voltage of 20 volts favors operation of the PBT as a power-device.

A Si PBT has also been realized, with IT = 22 GHz and imQZ = 30 GHz (Rathman and Niblack, 1988). A 20 GHz oscillator using this device had an FM noise level, 100 kHz away from the carrier, which was 17 dB lower than that of a MESFET oscillator with otherwise similar characteristics.

456 Microwave Semiconductor Devices

REVIEW OF THE PERFORMANCE OF MICROWAVE SEMICONDUCTOR DEVICES - 1990

This book has treated the physics and operation of a number of microwave semiconductor devices, which are now in use. In this final section we compare their performance. There are two primary groups of devices: Power devices and low-noise devices.

Microwave Sem..iconductor Power Devices

In Chapter 5 we discussed the limitations on the power output of mi­crowave semiconductor devices, and showed the performance of the two-terminal devices. Three-terminal devices were treated in Chapters 10-12. What are their relative merits as power devices, and how do these vary with the frequency? Figure 13.5 is a comprehensive graph which collects much of the relevant in­formation to answer this question.

As expected, Si BJTs yield the highest power at a few GHz, but MESFETs take over as the frequency approaches 10 GHz. MMIC versions of MESFETs have lower maximum output power at 10-20 GHz by about a factor of 5 com­pared with discrete devices. That factor changes as the frequency goes up, to a factor oftwo at 30 GHz, while at 60 GHz the highest power MESFET amplifier (about 100 mW) actually is designed as an MMIC (Hegazi et al., 1988).

The frequency range 20-100 GHz used to be dominated by IMPATTs, which show about an 1-1 roll-off in power. Recent developments in three­terminal devices have extended the frequency to which their output power follows the same 1-1 curve, to about 30 GHz. One should note that reviews 10 years ago indicated an 1-2 (or steeper) curve for MESFETs at all frequencies (see Sze, 1981). Still, IMPATTS have a power output several times that of the three-terminal devices in this range, with MESFETs and HFETs, and their variants described in Chapters 10 and 11, at power levels close to those of GUNN oscillators and amplifiers. A reasonable expectation for three-terminal device output power in the next few years can be obtained by extrapolating the MMIC curve with an 1-1 slope, resulting in 300 mW of power at 100 GHz. Three-terminal devices should also be expected to extend to frequencies above 100 GHz during that time.

Multipliers represent an interesting alternative source (Chapter 9). In the lower millimeter wave frequency range, recent progress with ISIS type varactors has resulted in greater maximum power and higher efficiency (50 %) than is available from single-device IMPATTs. The ISIS devices basically employ power-combining on the "mesa" level, and thus are effectively single devices. Of course, a solid state source is required at a lower frequency. We have also plotted the highest power output obtained from Schottky varactor doublers at and above 100 GHz - the curve shown is for balanced two-diode doublers (Erickson, 1990). These tend to be popular LO sources for millimeter wave

Chapter 13

10'

UI

~ .. X

I

a: til 10' x 0 Q.

.... ::> Q. .... ::> 0

457

~ ---"--'~11--rr-r-,-",----r-'--r-r-r-11'1 t I .----r-ITI , , , , '<--BJT ,

\

\ \ , '. '. <--MESFET

\ "'-....... ~~

to-GeAs IMPATT

x-HFET

+-HBT

MMIC--~' . ~~ \ \.. .... ~~.<--ISIS \" • '0 ,

BJT\ '"", "'-.... (~, .. '. ',,--- '- .... \.

GaAs , "".~ GLlN~ ............. >, ~~ '"\"._.

..... ', .. ~ \

\ \ \

\ \

• I I

•

'" :\ " '\

......... \\ \ S1 IMPATT

....... \. '\ " ~

\ \

<--InP GUNN • BAR ITT

.......... ,'l~~.Mult . \

. \

• \

FREQUENCY - GIiZ

\ \

Figure 13.5. Typical mazimum (single device) CW power output for mi­crowave semiconductor devices, versus frequency. A number of source.! have been compared to plot this graph. For special device.!, we have used data from Erickson (1990) (varactor multiplier.!), and Staecker et al. (1987) (ISIS var­actor.!), @1987 and 1990, IEEE.

458 Microwave Semiconductor Device~

mixers, and are employed up to 500 G Hz (about 0.5 m W) and somewhat higher. Off-scale in this diagram (about 100 p,W at 100 GHz) are RTDs (Chapter 4). Work is also going on to extend the power output of devices similar to the IMPATT, i.e. TUNNETTs and MITTATs (see e.g. Dogan et al., 1987).

The HBT (Chapter 12) is sure to figure prominently in future graphs of this type. At the present, a monolithic HBT amplifier at 10 GHz produced 4-5 W, comparable to the maximum power of MESFET MMIC devices. HBTs are advantageous in MMICs due to their compact size. Millimeter wave devices have not been tested of sufficient size as yet, to show the potential of the HBT in this range.

We remind the reader that power combiners (Chapter 7) have achieved significantly higher power output than the data given in Figure 13.5, which apply to single devices. For typical maximum power of electron tube sources, see Figure 7.1. The maximum power output is, of course, not the sole criterion for the choice of a semiconductor device. Very important are also factors such as the near-carrier FM and AM noise. Chapter 6 gives a review of such data for two-terminal devices, and Chapters 10-12 for three-terminal devices. These properties also tend to have large variations due to fabrication and material factors.

Low-Noise Receiver Devices

The main low-noise receiver devices are mixers, MESFETs and HFETs (Chapters 9-11). Noise figures and noise temperatures of MESFETs and HFETs were compared in Figures 11.39 and 11.41, and it remains to plot these together with the data for other types of receivers, see Figure 13.6. As before, we give the noise temperature at the input of a particular device, and do not include second stage noise, except for the case of mixers. An actual receiver system, which employs one of these devices for its first stage, thus may have a somewhat higher receiver noise temperature, depending on the gain of the first stage. One should also take into account the added noise due to transmission lines, dewar windows, or the atmospheric attenuation. The latter can be very substantial at millimeter wave frequencies (see, for instance, Wiltse, 1981). All these noise contributions can be calculated using the general methods described in Chapter 8, and added to the values of Figure 13.6.

The minimum realizable mixer conversion loss is essentially independent of frequency up to 100 GHz, which results in a typical minimum receiver noise temperature for room temperature operation of about 600 K. HFETs oper­ating at RT have considerably lower minimum noise temperatures up to 100 GHz, while the "break-even-point" for MESFETs is at about 60 GHz. Cool­ing to about 20 K decreases mixer SSB noise temperatures to about 100-200 K. Above 100 GHz Schottky diode mixer noise temperatures rise about lin­early with frequency. Cryogenic HFETs and MESFETs have much lower noise temperatures than the RT versions. Cryogenically cooled HFETs even rival

Chapter 13

ui 0: ::J I-

"' ffi n. ~ I-

UJ til ... o Z

10'

10· 10·

459

! 1) - MASER. RX. 4K

SIS MIXER

4K

10'

FAEUUENCY - 6HZ

Figure 13.6. Typical minimum receiver noise temperature for microwave semiconductor devices, versus frequency. Data for MASERs and SIS miz­erll have been included for reference. A number of sources have been com­pared to generate thill graph, but the most important 1I0urce is WEINREB, S., POSPIESZALSKI, M. W., and NORROD, R., (1988). "Cryogenic HEMT Low-Noise Receivers for 1.3 to 43 GHz Range," IEEE MTT-S Intern. Mi­crow. Symp. Dig., p. 945, @1988 IEEE.

460 Microwave Semiconductor Device8

the noise temperature at a few GHz of solid state masers, which have been included for comparison (the masers typically are high-gain amplifiers, which employ paramagnetic crystals such as ruby or Ti0 2 doped with FeH or Cr3+). The ultimate limit for amplifier noise temperature (traceable to the uncer­tainty relation in quantum mechanics) is the so-called quantum noise limit, T. = hl/(kBln2) (Siegman, 1971). The intrinsic noise temperature of masers approaches this limit, as indicated by the point for an 88 GHz maser (Sollner et al., 1979). The limiting intrinsic (device) noise temperature for a quantum mixer is the same, and one half of this value for a SSB mixer (see e.g. Wengler and Woody, 1987). An intrinsic noise temperature within 25% of the quantum limit has been measured for a SSB SIS mixer (Mears et al., 1990). Typical minimum SIS mixer receiver noise temperatures are also shown. Presently these are lower than those of Schottky barrier diode mixers in the millimeter wave/sub millimeter wave range. An even lower noise temperature (but with only about 1 MHz bandwidth) is attained by InSb hot electron mixers above 300 GHz.

The drastic lowering of HFET noise temperatures, especially in the mil­limeter wave range, is likely to continue in the next few years. SIS mixers (not described in this book) also are likely to show greater improvement than Schottky-barrier diode mixers. Other receiver characteristics which are of in­terest are bandwidth and saturation power. Three-terminal devices generally have excellent bandwidths. The SIS mixer has to be used with some caution since it has a fairly low saturation power, not too far above room temperature noise from a matched load in a typical mixer bandwidth.

CONCLUSION

Looking back about ten years, one could not easily then have predicted the excellent noise temperatures now achieved by HFETs, or three-terminal millimeter wave devices with close to 100 mW power output at 94 GHz. If a microwave semiconductor device book will be written ten years from now, it will undoubtedly discuss a number of new types of devices, which have capitalized on the rapid development of growth and fabrication techniques. The new devices may include some discussed in this chapter, and will probably use a new set of materials. Power-combining techniques can be predicted to increase the power output of semiconductor devices in the millimeter wave range. Of course, some completely new types of devices, not mentioned here, may also appear. The author's hope is that this book will help its readers understand the physics, operation, and characteristics of presently employed devices, as well as being a useful guide in following the future development of this exciting field.

Chapter 13 461

REFERENCES

ACTIS, R., CHICK, R.W., HOLLIS, M.A., CLIFTON, B.J., NICHOLS, K.B., and BOZLER, C.O. (1987). "Small-Signal Gain Performance of the Perme­able Base Transistor at EHF," IEEE Electron Device Lett., EDL-8, 66.

BOZLER, C.O., ALLEY, G.D., MURPHY, R.A., FLANDERS, D.C., and LINDLEY, W.T. (1979). "Permeable Base Transistor," Proc. 7th Bien. IEEE/Cornell Con!. Active Microw. Semicond. Devices, Ithaca, NY.

CAPASSO, F., and KIEHL, R.A. (1985) "Resonant Tunneling Transistor with Quantum Well Base and High Energy Injection: A Negative Differential Resistance Device," J. Appl. Phys., 58, 1366.

___ , Ed. (1990). "Physics of Quantum Electron Devices," Springer-Verlag, Berlin.

CHANG, C.Y., LIU, W.C., JAME, M.S., WANG, Y.H., LURYI, S., and SZE, S.M. (1986). "Induced Base Transistor Fabricated by Molecular Beam Epi­taxy," IEEE Electron Device Lett., EDL-7, 497.

DAVIS, R.H., and HOSACK, H.H.(1963). "Double Barrier in Thin Film Tri­odes," J. Appl. Phys., 34, 864

DOGAN, N.S., EAST, J.R., ELTA, M.E., HADDAD, G.1. (1987). "Millime­ter Wave Heterojunction MITATT Diodes," IEEE Trans. Microw. Theory Tech., MTT-35, 1308.

ERICKSON, N. (1990). "High-Efficiency Submillimeter Frequency Multipli­ers," IEEE MTT-S Intern. Microw. Symp. Dig., p. 1301.

HEGAZI, G., HUNG, H.-L.A., SINGER, J.L., PHELLEPS, F., HOLDEMAN, L., CORNFELD, A., SMITH, T., ALLISON, J., and HUANG, H. (1988). "V-Band Monolithic Power MESFET Amplifiers," IEEE Trans. Microw. Theory Tech., MTT-36, 1966.

HEIBLUM, M. (1981). "Tunneling Hot Electron Amplifiers (THETA): Am­plifiers Operating up to Infrared," Solid-State Electron., 24, 343.

___ , and FISCHETTI, M.V. (1990). "Ballistic Electron Transport in Hot Electron Transistors," in Physics of Quantum Electron Devices, F. Ca­passo, Ed., Springer-Verlag, Berlin, Ch. 9, p. 271.

HOLLIS, M.A., and MURPHY, R.A. (1990). "Homogeneous Field-Effect Transistors," in High-Speed Semiconductor Devices, S.M. Sze, Ed., John Wiley & Sons, New York, Ch. 4, p. 211.

HWANG, C.-G., NAVON, D.H., and TANG, T.-W. (1987). "Monte Carlo Simulation of the GaA8 Permeable Base Transistor," IEEE Trans. Electron Devices, ED-34, 154.

462 Microwave Semiconductor Devices

IOGANSEN, L.V. (1963). "The Possibility of Resonance Transmission of Elec­trons in Crystals through a System of Barriers," Zh. Eksp. Teor. Fiz., 45, 207 [Soviet Phys. JETP, 18, 46 (1964)].

KIELY, P.A., TAYLOR, G.W., ISABELLE, A., LEBBY, M.S., TELL, B., BROWN-GOEBELER, K.F., and CHANG, T.-Y. (1989). "An n-Channel BICFET in the InGaAlJjInAlAIJ/InGaAIJ Material System," IEEE Electron Device Lett., EDL-10, 304.

LUNARDI, L.M., SEN, S., CAPASSO, F., SMITH, P.R., SIVCO, D.L., and CHO, A.Y. (1989). "Microwave Multiple-State Resonant-Tunneling Bipolar Transistors," IEEE Electron Device Lett., EDL-10, 219.

LURYI, S. (1985). "An Induced Base Hot-Electron Transistor," IEEE Electron Device Lett., EDL-6, 403.

MEAD, C.A. (1960). "Tunnel-Emission Amplifiers," Proc. IRE, 48, 359.

MEARS, C.A., HU, QING, RICHARDS, P.L., WORSHAM, A.H., PROBER, D.E., and RAISANEN, A.V., (1990). "Quantum-Limited Heterodyne De­tection of Millimeter Waves Using Superconducting Tantalum Tunnel Junc­tions," Appl. Phys. Lett., 57, 2487.

PRASAD, S., LEE, W., and FONSTAD, C.G. (1988). "Unilateral Gain of Heterojunction Bipolar Transistors at Microwave Frequencies," IEEE 7rans. Electron Devices, ED-35, 2288.

RATHMAN, D.D., and NIBLACK, W.K. (1988). "Silicon Permeable Base Transistors for Low-Phase-Noise Oscillator Applications up to 20 GHz," IEEE Intern. Microw. Symp. Dig., 537.

SEO, K., HEIBLUM, M., KNOEDLER, C.M., OH, J.E., PAMULAPATI, J., and BATTACHARYA, P. (1989). "High-Gain Pseudomorphic InGaA8 Base Ballistic Hot-Electron Device," IEEE Electron Device Lett., EDL-10, 73.

SIEGMAN, A.E. (1971). "Introduction to Lasers and Masers," McGraw-Hill, N.Y.

SOLLNER, T.C.L.G., CLEMENS, D.P., KORZENIOWSKI, T.L., McINTOSH, G.C., MOORE, E.L., and YNGVESSON, K.S. (1979). "Low-Noise 86-88 GHz Traveling-Wave Maser," Appl. Phys. Lett., 35, 833.

STEER, M.B., and TREW, R.J. (1986). "High-Frequency Limits of Millimeter­Wave Transistors," IEEE Electron Device Lett., EDL-7, 640.

SZE, S.M. (1981). "Physics of Semiconductor Devices," Second Edition, John Wiley & Sons, New York.

___ , Ed. (1990). "High-Speed Semiconductor Devices," John Wiley & Sons, New York.

Chapter 13 463

TAYLOR, G.W., and SIMMONS, J.G. (1985). "The Bipolar Inversion Chan­nel Field-Effect Transistor (BICFET)- A New Field-Effect Solid-State Device: Theory and Structures," IEEE Tran,. Electron Device8, ED-32, 2345.

WENGLER, M.J. and WOODY, D.P. (1987). "Quantum-Noise in Heterodyne Detection," IEEE J. Qu. El., QE-23, 613.

WILTSE, J .C. (1981). "Introduction and Overview of Millimeter Waves, in Infrared and Millimeter Waves, K.J. Button and J .C. Wiltse, Eds., Aca­demic Press, New York, Vol. 4, Ch. I, p. 1.

YOKOYAMA, N., MUTO, S., OHNISHI, H., IMAMURA, K., MORl, T., and INATA, T. (1990). "Resonant-Tunneling Hot Electron Transistors (RHET)," in Physics of Quantum Electron Devices, F. Capasso, Ed., Springer-Verlag, Berlin, Ch. 8, p. 253.

FURTHER READING

CAPASSO, F., Ed. (1990), cited above.

SHUR, M. (1990). "Physics of Semiconductor Devices," Prentice Hall, Engle­wood Cliffs, NJ.

SZE, S.M., Ed. (1990), cited above.