Study of the effect of the deposition RF power on the characteristics of microcrystalline Silicon-Germanium thin films produced by PECVD

Hydrogenated microcrystalline Silicon-Germanium (μc-SiGe:H) thin films were deposited using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique from a gas mixture of SiH 4 , GeH 4 , H 2 and Ar at a substrate temperature of 200 ° C. The films were deposited at a pressure of 1.5 Torr, while the RF power was varied in the range of 20 W to 35 W. Structural, optical and electrical characterization was performed in the films, Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to analyze the hydrogen bonding of silicon and germanium, while Raman spectroscopy was used in order to analyze the crystallinity of the films. Through the optical and electrical characterization of the films, parameters such as the optical band gap (E g ) and the activation energy (E A ) were obtained, respectively. The conductivity of the films changed up two to orders of magnitude from dark conditions to illumination AM 1.5. Finally, the correlation between deposition RF power and the film properties is presented.