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

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 degrees 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 10(5), 0.12 V/dec and 0.9 V, respectively, were obtained on TFTs with the nc-SiGe:H active layer deposited at 25 W.