Thin film transistor

Introduction

A TFT monitor uses thin-film transistor technology for the ultimate LCD display.

It replaces the old style cathode ray tubes (CRTs).

Semiconductor

The first TFT for LCD was made of Cd-Se semiconductor thin films, Though it has a better performance, its commercialization is still not success.

TFTs can be formed by three different silicons, they are: crystalline silicon, poly-silicon and amorphous silicon.

Mechanism

Types

P-channel TFT: switched ON- ‘-’voltage on the gate,switched OFF- ‘+’ voltage on the gate. N-channel TFTswitched ON- ‘+’voltage on the gate,switched OFF- ‘-’ voltage on the gate.

Benefits

• Less current compared to CRT.

• This allows for very fast re-drawing of the display, as the image is re-painted or refreshed several times per second

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