Effect of Delta Doping in a-SiN:H Thin Film on the Mobility of Thin Film Transistors

Abstract

Amorphous silicon modulation-doped field effect transistors using the heterostructure of phosphorous-contained a-SiN:H and intrinsic a-Si:H films have been fabricated by plasma enhanced chemical vapor deposition of SiH4, PH3, Ar and NH3 gases. The characteristics of the devices have been investigated and compared with conventional amorphous silicon thin film transistors. Various studies have been carried out on the properties of the materials of a-SiN:H films that were deposited with a varied delta-doping thickness and it was found that the Vth shifted from 2.5 to 4.5 V with an increase in the delta-doping thickness from 0 to 200 Å. The μn changed also from 0.19 to 0.38 cm2/V·sec.