Bottom gate structure a-Si ∶ H TFT array was deposited by standard PECVD process at 300 ℃ on Kapton E plastic substrate with thickness of 50 m. The structure of a-Si ∶ H film was characterized by IR spectrum. The electrical conductivity of a-Si ∶ H film and n

+

a-Si ∶ H film is measured by two probes and four probes method

respectively. The H atom is of 15.6% content in a-Si ∶ H film and mainly appeared in SiH and SiH

2

group. The electrical conductivity of a-Si ∶ H film is 8.210

-7

~8.810

-6

S/cm

and that of n

+

a-Si ∶ H film is 3.810

-3

S/cm. The TFTs have a threshold voltage of ~5 V

sub threshold slope of ~2.5 V/dec

linear mobility of ~0.113 cm

2

/(Vs) and on/off current ratio of ~10

5

. The results show that the a-Si ∶ H TFTs on plastic substrate fabricated in this process can be used in TFT-LCD and some other switch addressable circuits of flat panel display.