TERAHERTZ TRANSISTORPresented by

Sumit kumar Saha

Elec. & Comm. Engineering

Academy of Technology

What is Terahertz Transistor?

• 1 Tera = 1,000,000,000,000

• Transistor = “Transfer of Resister”

A transistor is a semiconductor device used to amplify and switch electronics device.

A Terahertz transistor can ran 1 trillion cycle per second

Basic Transistor

• Has at least 3 terminal for connection with external circuit

• With one terminal can operate the current flow through other two terminal

• Because the controlled output power can be much more than the controlling input power, the transistor provides amplification of a signal

• With controlled terminal we can also operate it as switch

continued……

Basic Transistor

• According to the structure the types are

BJT, JFET, MOSFET, IGBT, etc.

BJT or FET ?

• The parameters are:-

1. Input resistance

2. Noise

3. Thermal stability

4. Gain-bandwidth product

5. speed

Which is suitable for Terahertz application ?

▫ FET. Specially MOSFT.

Operation of MOSFET transistor

1. Transistor used as switch

2. Transistor used as amplifier

Moore’s Law

• Doubling the number of transistors per integrated circuit in 18-24 months

• The capabilities of many digital electronic devices are strongly linked to Moore's law: processing speed, memory capacity, sensors and even the number and size of pixels in digital cameras

Continued….

Moore’s Law

• First observed at 1965

• True for last 45 years

What is the problem ??

• Power consumption starting it rise exponentially

• Driven by

oTransistor Off-state leakage

oTransistor Gate leakage

oHigh operating voltage

• Soft error rate

Power Consumption Rate Transistor Off-state Leakage

Gelsinger’s Slide from ISSCC 2001

Transistor Gate Leakage Soft Error Rate

High Operating Voltage

• To solve this problem we have to consider another three parameters

Source and drain resistance

Source and drain capacitance

Gate delay and drive current

Source and Drain Resistance

Continued……

Source and Drain Resistance

Source and Drain Capacitance

Gate Delay and Drive Current

• Gate delay is the time it takes for current to travel from the source to the drain (across the channel)

• Drive current is the amount of current that flows when the transistor is turned on.

• Smaller gate delay and larger drive current translates into FASTER transistors and circuits.

Fundamental Challenge For This

Decade • Continue Moore’s Law without Exponential

increase in Power Consumption

• Intel introduced two important technology

Depleted substrate transistor & Raised source-drain

High k-gate dielectric

• Our long term approach is:

TERAHERTZ TRANSISTER

Depleted substrate transistor And

Raised source & drain

High K-Gate Dielectric

Solution of each problem using

TERAHERTZ TRANSISTOR and

satisfy the Moore’s Law

Solution of Off-state Leakage

Solution of transistor gate leakage by

gate dielectric

Solution of problem with high

operating voltage

Solution of Soft Error Rate

Transistor Performance Comparison

Advantages of Terahertz Transistor

• Reduces leakage current by 10,000X for the same capacitance

• Increased reliability • High speed • Eliminates subsurface leakage• Minimizes soft error rates• Eliminates floating body effect• Less voltage required to turn ON transistor• No leakage path through substrate• Lowest junction capacitance• Ease of circuit design

Application of Terahertz Transistor

• Due to its very difficult fabrication process the cost is high. So, these type of transistors are not used in general purpose.

• Intel launched world first THz transistor of speed 2THz in 2001

• Also AMD, IBM made their first terahertz transistor in their lab of speed 3.3THz(AMD) and 2THz(IBM)

• Intel launched 10GHz processor in 2005 and their next processor of speed 20GHz will launched in upcoming year.

Continued…..

Applications of Terahertz Transistor

Today they are used in:• Radiotelescopy and

Sub-MilimeterAstronomy Devices

• Medical Imaging Devices

• Security Devices• Manufacturing, Quality

Control, and Process Monitoring

Non-planer Tri-Gate Transistor

Thank you