Organic Field EffectTransistor

Santosh

B10130

Introduction

• Bardeen, Shockley, and Brattain invented the world's first transistor in 1947

• The first OFET was reported in 1986.

• It was based on a film of electrochemically grown polythiophene.

• Four years later, the first OFET employing a small conjugated molecule (sexithiophene) was fabricated.

Device operation

OFETs are composed of three terminals

1. source

2. drain

3. Gate

as well as a semiconductor layer and an insulating layer between the semiconductor and gate.

There are two common device configurations used in OFETs

1. Top contact

2. Bottom contact

Top contact

When the source and drain electrodes are evaporated on the top of the organic material.

Bottom contact

When the source and drain electrodes are evaporated on the dielectric before depositing the organic semiconductor.

Characteristic of OFETs

When we are applied voltage to the gate induces an electric field through the dielectric and causes the formation of an accumulation layer of charges at the interface of the semiconductor deposited.

OFET characteristic can be classified as:

a. Transfer Characteristic

b. Output Characteristic

These characteristic depends on whether Vgs is varied while Vds is kept constant, or Vds is varied while Vgs is kept constant.

Characteristic of OFETs

Transfer characteristic

Characteristic of OFETs

Output characteristic

Organic Molecule - Pentacene

Pentacene Molecule Organic semiconductor

Composed of five Benzene rings

Polycyclic Aromatic hydrocarbon

Easy to synthesize

High carrier mobility

Pentacene mobility v/s other organics

Organic Field effect Transistor

Advantage DisadvantageCost effective Thermal stability

Large Selection of Material Chemical Stability (Oxidation)

Lighter and flexible

Future of OFET

Skin Cancer treatments

Portable compacts screens

Smart textile

References

1. http://iopscience.iop.org/1468-6996/10/2/024313/

2. https://smartech.gatech.edu

3. http://www.slideshare.net/organic-transistors?from_search=12

Questions???