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 V_th shifted from 2.5 to 4.5 V with an increase in the delta-doping thickness from 0 to 200 Å. The μ_n changed also from 0.19 to 0.38 cm²/V·sec.

Keywords:

• a-Si:H thin film transistor
• delta doping
• modulation-doped

Acknowledgments

This work was supported by the Regional Innovation Center Program (ADMRC) of the Ministry of Knowledge Economy and the second phase of the Brain Korea 21 Program in 2008.