Study of nanocrystalline silicon-germanium for the development of thin film transistors

Abstract

In this work, we study the effect of the deposition RF-power on the structural, optical and electrical properties of hydrogenated nanocrystalline silicon-germanium (nc-SiGe:H) thin films obtained by plasma enhanced chemical vapor deposition (PECVD) at substrate temperature of 200 °C. The objective is to produce films with high crystalline fraction in order to be used as active layers in thin film transistors (TFTs). Bottom-gate (BG) thin film transistors were fabricated with nc-SiGe:H active layers, deposited at different RF-power. Values of ON-OFF current ratio, subthreshold slope and threshold voltage of 105, 0.12 V/dec and 0.9 V, respectively, were obtained on TFTs with the nc-SiGe:H active layer deposited at 25 W.