Growth temperature and microstructural differences in hydrogenated amorphous silicon deposited on glass substrates

Minani, Evariste

Growth temperature and microstructural differences in hydrogenated amorphous silicon deposited on glass substrates

Master Thesis

2002

Publisher

University of Cape Town

Department

Department of Physics

Faculty

Faculty of Science

Abstract

Hydrogenated amorphous silicon (a-Si:H) is an important thin film semiconductor with a wide variety of applications in microelectronics and optoelectronics. However, it is metastable and photodegrades after a moderate light illumination (Staebler-Wronski effect). The most stable material has been suggested to be at the edge of crystallinity with microcrystalline inclusions. Using a combination of positron annihilation and X-ray diffraction techniques, the microstructure of hydrogenated amorphous silicon grown by hot wire chemical vapour deposition on glass substrates at different substrate temperatures ranging between 300°C and 500 °C is examined. In previous studies the crystallisation was accompanied by a relaxation of defect structure with an increase in free volume at positron annihilation site. In this work, both techniques show a relaxation of the network with increasing growth temperature, leading to a higher degree of ordering, shorter bond lengths, and a reduction in the average size of defects in the material.

Description

Includes bibliography.

Keywords

Physics

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