Fabrication of a‐SiGe structure by rf sputtering for solar cell purposes

Abstract

The deposition and electronic properties of a-SiGe and a-Si layers for thin-film solar cell applications are discussed. Technological parameters were developed for good layer quality of amorphous material. An inverse relation was discovered between the resistivity and the flow of hydrogen without annealing after deposition. Antimony was found to be a good doping material.1. Introduction Radio frequency (rf) sputtering is an efficient process for preparing amorphous semiconductor and metal layers on different sheets as substrate materials [1,2]. In this work we discuss the deposition process and electronic properties of a-SiGe and a-Si layers for use in thin-film solar cell applications. We have tested several substrate materials for thin-film deposition. The substrates used were Si wafer with oxide isolation, glass and a special plastic foil. We have investigated the sticking properties of the thin film for different treatment of the surface of the various substrate materials.The building in of the hydrogen and of the dopant materials (7N-Al, 5N-Sb) was investigated with different target materials and with different flows of hydrogen while the deposition and the annealing parameters were changed. The layer thickness was determined by alpha-step profiling. The Ge content was determined by Rutherford backscattering (RBS) measurements. The electrical parameters were determined by temperature-dependent van der Pauw measurements.

Effects of Bias on Optical and Chemical Bonding Properties of Germanium Carbon Films

“…Researches on the group IV amorphous semiconductors with relatively narrow optical band gap have been aggressively reported for use in hetero-structure devices and as an absorber material for a tandem solar cell. There have been many reports on a-SiGe:H and a-SiC:H films [1,2], whereas a-GeC:H films have attracted less attention for applications in optoelectronics [3]. However, a-Ge 1-x C x :H films can provide apparently tunable band gap over a very wide range which is important for photovoltaic applications [3][4][5] and high absorption coefficient indicating that a-Ge 1-x C x :H needs much thinner layer than silicon to absorb most of solar photons, which not only means less manufacturing cost but high efficiency of the solar cell [6].…”

Optical and electrical properties of undoped and oxygen-doped a-GeC:H films prepared by magnetron sputtering

“…The latter is realized by alloying germanium with either silicon or carbon. There have been many reports on a-SiGe:H films [1], whereas aGeC:H films have attracted less attention owing to their inferior properties from the standpoint of application to optoelectronics [2]. However, the study of a-GeC:H films is of interest in fundamental research on optical and electronic properties of tetrahedrally bonded amorphous semiconductors.…”