Applications of diamond films

Lecture 5

CVD diamond devices and components

microwave transistor on diamond wafer

UV and X-ray detectors

IR windows for gyrotron and CO2 lasers X-ray lenses and screens

thin membranes

Cutting tools

CVD diamond thermal spreaders for microwave electronic devices (transistors).

Examples of size: 4.6 х 0.9 х 0.5 мм 8.6 х 1.4 х 0.5 мм

Thin diamond films on AlN ceramics

AlN dielectric heat spreader, 18 mm diameter.Diamond coating increases thermal conductivity from 1.7 to 10.0 W/cmK.

AlN before diamond ►deposition

◄ Coated with black diamond

V.G. Ralchenko, Russian Microelectronics, 2006, Vol. 35, No. 4, p. 205.

growth rate 7.9 μm/h;film thickness up to 150 μm

Thermal conductivity measurements by laser flash technique

CVD diamond detectors

D. Meier, RD42 Collaboration Rep. 1996

Charge collection distanced = µτE

RD42 Collaboration (CERN) data forDe Beers CVD diamond samples (poly): d = 200 µm (year 2000) dmax ≈ 350 µm present

Stable up to dose ~1015 cm-2

under protons, neutrons, pions.

GPI samples

0 200 400 600 800 1000 12001E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0,01

0,1

1

10

2

1

Res

pons

ivity

(A/W

)

Wavelength (nm)

CVD diamond UV detectorssolar-blind photoresistors

Interdigitizing electrodes on polished diamond. Cr(20 nm)/Au(500nm) strips 50 µm wide, the gap between electrodes is 50 µm.

Spectral discrimination UV/Vis of 105.Dark current of the order of 1 pA.

V.G. Ralchenko et al. Quantum Electronics (Moscow, 36 (2006) 487.

Photoresponse of nucleation (1) and growth sides

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

2 3 4 5 6 7

RAS SC A010

4.8x4.8x0,49 mm3

=4.1 nmAg 40 m grid

Res

pons

ivity

(A/W

)

Photon Energy (eV)

100V

200V

Eg

38±5 meV

GPI-RAS DiamondSpectral Photonductivity: JDoS

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

2 3 4 5 6 7

RAS SC A010=4.1 nm

Ag 40 m grid200V

Res

pons

ivity

(A/W

)

Photon Energy (eV)

38±5 meV50±5 meV

E6 SC-DG

Low surface recombination and small Urbach tail.

The recovery of photoconductivity is more than 6 orders of magnitude and saturates around 5 V/µm.

Band gap Eg = 5.45 eV. Light absorption and e-h pairs generationfor photons with λ <225 nm, no absorption in the visible and IR.

► solar-blind radiation-hard photodetectors (no filters are needed)

SC CVD diamond UV detectors

0

0,2

0,4

0,6

0,8

1

0 2 4 6 8

Am

plitu

de

Scan direction (mm)

1 2 3 4 5 6 78

02468

101214161820222426

12

34

56

78

2D-UV detector: mapping the laser beam16-pixel matrix sensor on 1 cm2 polycrystalline diamond: G. Mazzeo et al. DRM. 16 (2007) 1053

Colonne (x)

Rig

he (y

)

0

4,167

8,333

12,50

16,67

20,83

25,00

6 5 4 3 2 19 8 7

1

2

3

4

5

6

7

8

9

Rows and columns are electrodes

on two sides of the diamond sample. Sensor electronics

Output signal : 1 mm2 beam illuminates the pixels along the row direction. incident measured

Test monochromatic beam profile

1 2 3 4 5 6

S1

S2

S3

S4

S5

S6

M. Girolami, P. Allegrini, G. Conte, S. Salvatori, D. M. Trucchi, A. Bolshakov, V. Ralchenko “Diamond detectors for UV and X-ray source imaging”, IEEE-EDL 33 (2012) 224-226.

PastUV, X-ray Source Imaging

• 36-pixel array (0.75 × 0.75 mm2)

• Poly 1 cm2 RAS 270 um• Contacts – Ag 50-200 nm• Cu-Ka, 8.05 keV

• ArF 193 nm, 3 mW

UV, X-ray Source Imaging by 2D detectors

X-ray tube beam profile when scanned across the detector

ArF excimer laser beam profile

On-line diamond X-ray detectorsDiamond membrane: 11 µm thickness,window of 7 mm diameter.

Source: X-ray tube with tungsten anode. Electrodes Au/Ti, Ø3 mm. Dark current ~100pA. Photocurrent/dark-current ratio: 8x103 at Ua=50 kV, j=15 mA.

X-ray transmission (50 keV) > 98%.

V. Dvoryankin et al. Lebedev Physical Institute Reports, No. 9 (2006) 44.

p-type conductivity on H-terminated diamond surface: 2D hole layer

Hdiamond

H-terminated layer

Microwave plasma

less than 6 nm

Hole density is evaluated from C-V characteristics

G. Conte et al, NGC 2011, Moscow

1994: H-terminated diamond based FETH. Kawarada, et al., Appl. Phys. Lett. 65

(111) Surface with C-H bonds

• Surface band bending where valence-band electrons transfer into an adsorbate layer: “transfer doping model”.

• Shallow hydrogen induced acceptors.

♦ carriers density value 1013 cm-2

♦ hole mobility 100-130 cm2/Vs♦ activation energy 1.6-4.1 meV

Device Layout

25 μm ≤ WG ≤ 200 μm0.2 μm ≤ LG ≤ 1 μm

Small H-terminated area for leakage current reduction and electric field confinement.

2D Hole Channel

Drain(Au)

Gate(Al)Source

(Au)Source

(Au)

CVD Diamond

WG

Device Technology Issues MESFET technology issuesBatterfy-shaped design

-10

0

10

20

30

40

0,1 1 10 100

MAG [dB]|H

21|2 [dB]G

ain

(dB)

Frequency (GHz)

-20 dB/dec.

VGS=-0.2 V, VDS=-10 V

Gain = 15 dB@ 1 GHz

Eapplied= 0.5 MV/cm

WG=25 μm

fMAX = 23.7 GHz

fT = 6.9 GHz

Polycrystalline Diamond RAS PolyD4

fMAX/fT=3.5

LG=0.2 μm

PastSurface Channel MESFETs

G. Conte, E. Giovine, A. Bolshakov, V. Ralchenko, V. Konov“Surface Channel MESFETs on Hydrogenated Diamond”, Nanotechnology 23 (2012) 025201.

-10

0

10

20

30

40

0,1 1 10 100

MAG [dB]|H

21|2 [dB]

Gai

n (d

B)

Frequency (GHz)

Single Crystal DiamondRAS P7MS

Wg=50 μm

fMAX =26.3 GHz

fT = 13.2 GHz

Gain = 22 dB @ 1 GHz

fMAX/fT=1.8

MESFET frequency characteristics

diamond

2

1 graphite

2 laser beam

1- buried graphite; 2 - contacts

Fast CVD diamond bolometerVery thin buried graphitized layer as resistor.Fast dissipation of absorbed energy – quick response. Fabrication procedure:(i) C+ ion implantation in polished CVD diamond:energy 350 keV, dose 81015cm-2.(ii) Contacts – graphitic pillars by C+ implantation at variable energy of 20 to 350 keV.(iii) Annealing in vacuum at 1500ºC for 1 hour. ► Buried graphite strip: 2 mm total length, 70 μm wide, thickness 220 nm, depth 265 nm.Segments of 70 and 300 μm long.

Resistance @298 K is R0=300-1200 Ohm.Linear temperature dependenceR(T)=(-1.4710-4 K-1)R0

T.I. Galkina, Physics of Solid State (St. Petersburg), 49 (2007) 621.

0 20 40 60 80 100-1.0

-0.8

-0.6

-0.4

-0.2

0.0

Nor

mal

ized

resp

ense

s, a.

u.

Time, ns

Test of diamond bolometer

Pulsed irradiation with a nitrogen laser (λ=337 nm, τ~ 8 ns).Beam spot size 90 μm.

Measured signal (circles) and modeling (solid line).Response signal ≈20 ns (FWHM), very fast for bolometer-type sensors

z

r

L1

L2

L3

c1 11

1

c2 22

2

c3 33

3

R

0 G1

G2 0

0

Layered structure for simulation of the bolometer response kinetics.

Raman diamond lasers use Stimulated Raman Scattering (SRS)

For polycrystalline CVD diamond:Kaminskii, V. Ralchenko, et al. Phys. Stat. Sol. (b), (2005). For single crystal CVD diamond:A.A.Kaminskii, R.J. Hemley, et al. Laser Phys. Lett. (2007).

Stokes and anti-Stokes lines.SRS intensity comparable to pump

pulsed pump Single pass geometry

● SRS is observed only at high enough intensities.● Advantages of diamond:- large Raman shift 1332 cm-1- high gain g>11 cm/GW.

0

1

2

3

4

5

6

7

8

9

anti-Stokes

Stokes

pump

0 +

1

0 -

1

0

Log

inte

nsity

0 + 2

1

0 +

1

0

0 - 2

1

0 -

1

pump

ASt1

ASt2St

2

St1

spontaneous RS

stimulated RS excitation at λ=1.06 µm;three anti-Stokes lines

Wavelength conversion range achieved experimentallypolycrystalline CVD diamond

0,1 1 100

20

40

60

80

2.033 m0.466 m

Tran

smitt

ance

, %

Wavelength, m

Excitation wavelengths: 0.53 μm, 1.06 μm, 1.32 μmPulse duration: 15 ns, 10 ps and 80 ps. Yellow emission at 573 nm;

5 kHz (ns), 1.2 W output power;conversion efficiency of 63.5%.2.2 W with ps pulses (2010)

Single crystal are more efficient. Raman laser on SC CVD diamond:R. Mildren et al. Opt. Lett. (2009)

Latest result: A continuous-wave (cw) operation of a diamond Raman laser at 1240 nm with power 10.1 W. A. McKay et al. Laser Phys. Lett., 10 (2013) 105801.

Crystal Shift (cm-1)

Gain (cm/GW)

Phonon lifetime (ps)

Reference

Lithium formate LiHCOO·H2O

1372 3 10 K. Lai, Phys. Rev. B (1990).

natural diamond 1332 15 5 A. McQuillan, Phys. Rev. A (1970). CVD diamond 1332.5 >11 4.2 A. Kaminskii,

Laser Phys. Lett. (2006) Calcium carbonate CaCO3

1086 1.6 8.3 G. Pasmanic, LFW, Nov 1999

Sodium nitrate NaNO3 1059 7 10 G. Pasmanic, LFW, Nov 1999 Barium nitrate Ba(NO3)2 1040 10 26 A. Eremenko, Kvant.Electron. (1980) Potassium yttrium tungstate KY(WO4)2

905 3.6 1.5 A. Ivanyuk, Opt. Spectrosc. (1985)

Lead tangstate PbWO4 901 1.5 A. Kaminskii, Opt. Commun. (2000) Yttrium vanadate YVO4 890 3.5 A. Kaminskii, Opt. Commun. (2001)

Diamond, having highest gain, can be the next commercial crystalline medium for Raman shifters.

Commercial SRS-active crystalline materials withlaser frequency shift (ωSRS) more than 850 cm-1

A.A. Kaminskii, Laser Physics Letters, 3 (2006) 171.

Institute of Photonics, University of Strathclyde, UKIndustrial Diamond Rev. No. 4, 2008.

Diamond Raman laser

C. Wild, SMSA 2008, Nizhny Novgorod

Diamond window for IR cw lasers

ANSYS program, finite element analysis.● all absorbed heat dissipates via cooled edges.●Laser parameters: beam diameter 10 mm; incident power 5.0 kW; absorption coeff. =0,1 см-1 (at 10.6 μm).Result - heating ΔT<9°C.

Modeling: radial temperature profile

-15 -10 -5 0 5 10 15

26

28

30

32

34

d=5x2mm k=18W/cm*K P=5KW

T (0 C)

Distance from center (mm)

, cm-1

0,03 0,06 0,1

CVD diamond, 25 mm diameter, 1.2 mm thickness

Experiment:Exposed to a fiber Nd:YAG cw laser for 1 min; power 10.0 kW, beam diameter 5 mm, Result - window survived

V.E. Rogalin et al. Russian Microelectronics, 41 (2012) 26.

Gyrotrons – generators of powerful mm waves (~100-200 GHz)

very low absorption (low loss tangent) high mechanical strength (Young’s modulus, E) low dielectric permittivity, . low thermal expansion coefficient, high thermal conductivity, k, 

Properties of some materials important for mm-waves windows(T=293 K and f=145 GHz)

Material tan(10-4)

kW/cmK

10-6 K-1

EGPa

Fused quartz 3.8 3 0.014 0.5 73

BN 4.3 5 0.35 3 60

BeO 6.7 10 2.5 7.6 350

Sapphire 9.4 2 0.4 8.2 380

Au-doped Si 11.7 0.03 1.4 2.5 160

Diamond 5.7 0.08* 0.03**

20 0.8 1050

*Diagascrown/GPI sample [B. Garin et al. Techn. Phys. Lett. 25 (1999) 288]**DeBeers sample [V. Parshin et al. Proc. 10th Int. ITG-Conf. on Displays and Vacuum Electronics, 2004

**DeBeers sample [V. Parshin et al. Proc. 10th Int. ITG-Conf. on Displays and Vacuum Electronics, 2004]

Requirements to gyrotron window material:

Vacuum-tight CVD diamond windowsbrazed to copper cuffs

TESTSThermal cycling: ● 25-750-25C and (–60)-(+150)C ● 8 hours heating at 650C.

No degradation in vacuum tightness.

Window diameter 60 mm and 15 mm

Loss tangent ~10-5.

V. Parshin, 4th Int. Symp. Diamond Films and Relat. Mater., Kharkov, Ukraine, 1999, p. 343.

CVD diamond to manage synchrotron radiationSynchrotrons generate extremely bright radiation by electrons orbiting in magnetic field with speed close to velocity of light.Photons in a broad IR to X-ray range; power density of hundreds W/mm2.

Diamond instead of Si for: ● beam attenuators; ● fluorescent screen for beam monitoring; ● X-ray and UV detectors, ● monochromators (first tested at European Synchrotron, Grenoble, in 1992), (only single crystals appropriate)

Synchrotron Soleil , Paris

Water cooled IR window from Diamond Materials, Germany

Transmission of 0–20 keV radiation through 20 μm thick beryllium, diamond and silicon.

High transparency of diamond for X-rayscan be utilized for making X-ray lenses

C. Ribbing et al. Diamond Relat. Mater. 12 (2003) 1793.

Principle of X-ray focusing by a refractive lens

For X-rays refractive index n=1-δ, (δ<<1)► a hole acts as the lens

X-ray diamond lenses of 15 x 40 mm2 size with relief depth of 100 and 200 μm. Four parabolic lenses are formed on each 110 μm thick diamond plate.

Diamond films of ca. 110 m thickness

Refractive CVD diamond X-ray lensproduced by molding technique

Geometry of X-ray focusing test.

A. Snigirev, Proc. SPIE, Vol. 4783 (2002) p. 1.

Lens test at synchrotron (ESRF, Grenoble):Beam focusing at 2 μm diameter; focal distance 50 cm; lens gain: 22-100.X-ray transmission 80% @ 38 keV;X-ray power density 50 W/mm2 – long term (16 hours) stability (experiment);up to 500 W/mm2 – acceptable (simulation).

C.-S. Zha et al. High Pressure Research, 29 (2009) 317

CVD diamond anvils for high-pressure/high-temperature experiments

CVD-based diamond anvils have strength that is at least comparableto and potentially higher than anvils made of natural diamond.

Reparation of damaged anvil combined CVD-natural diamond anvil.

CVD-covered anvil immediately after the growth.

The same anvil after removing of the polycrystalline material, reshaping, andpolishing to anvil with 30μm in diameter of the center flat culet.

Test: successful HPHT measurements on hydrogen at megabar pressures.

Opal (and inverse opal) as photonic crystal

opal and inverse opal structures

A.A. Zakhidov, Science, 282 (1998) 897.

Silica opals are made by self-assembly of SiO2 spheres into face-centered cubic (fcc) crystals.

The narrowest channel (pore) diameter ≤ 39 nm for balls of 250 mm diameter.

Pores in opal lattice can be filled with other materials to make a composite or inverse structure (replica).

A.A. Zakhidov, Science, 282 (1998) 897.

Diamond inverse opal produced by replica techniqueSeeding with ND partciles, diamond deposition in microwave plasma

Inverted opal made of amorphous Si Produced at A. Ioffe Phys.Technical Inst. RAS, St. Petersburg

Period 310 nm, pore diameter ~100 nm. Plate thickness 400 µm.

Thermal decomposition of SiH4 in pores of SiO2 opal, followed by SiO2 matrix etching.

Seeding with NDInverted Si opal – porous structure

Direct opal diamondL = 310 nm, 25 layers of spheres

Diamond opal. Cross section 10 µm below the growth surface.

Raman spectra excited in UV (244 nm), top, and in the visible (488 nm), bottom, regions

1200 1300 1400 1500 1600 17000

5

10

15

20

25

ex=488 nmIn

tens

ity, a

.u.

Raman shift, cm-1

1360 cm-1

1336 cm-1

1334 cm-1 1585 cm-1

1585 cm-1

1623 cm-1

ex=244 nm

Next step: diamond deposition in Si opal template followed by the Si etching.A lot of a-C and graphite in the deposit.Graphite etching by oxidation in air at Т = 500ºС.

Clear diamond peak at 1332 cm-1 in UV. Still graphite-like is present.

Sovyk D. N. et al. Physics of the solid state. 55 (2013) 1120.

Diamond shells (20 nm thick) with nanographite partciles inside.(111) face.

Diamond opal as photonic crystalReflection spectra from inversed Si opal (period 310 nm)and direct diamond opal (period 260 nm) at angle 11° to (111) plane.Bragg reflection peaks are clearly observed.

D-opal

Si inversed opal

Conclusions

● Polycrystalline diamond films and single crystals of high purity and large size can be produced by CVD technique.

● The properties of CVD diamond approach (in some cases exceed) those known for the best natural single crystal diamonds.

● Potential application of the CVD diamond include, in particular: -- detectors of ionizing radiation;- - X-ray, optics, IR and microwave optics for CO2 lasers, gyrotrons,

etc;- - radiation-hard, high-temperature, high-power electronic devices;- - Raman lasers- - GHz-range devices based on surface acoustics waves;-- new applications…

GPI Diamond Materials Lab