High electrical conductivity of P type a-SiGe:H films deposited by PECVD

Abstract

Highly doped films P type a-SiGe:H and undoped a-SiGe:H films with different germanium content were studied by electrical and morphology characterization for increase their electrical conductivity value (maximum value found: 6.1 × 10−2 Ω−1cm−1). The samples were deposited by low frequency (LF) PECVD at 200°C, 1.2 Torr of pressure at RF frequency of 110 kHz. Boron was used as dopant in the range from 0.26 % to 4% in steps of 0.26% approximately. The most conductivity films were obtained at 4% boron in gas phase, this characteristic made the material attractive for development of TFTs as source and drain regions. Additionally, the p type material allows the possibility of producing the CMOS technology in the TFTs technology, also it may be deposited in flexible substrates and used in solar cell as emitter. On the other hand the a-Ge is used for passivating the surface of high-purity Ge detectors.