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Title: Properties of CdTe films grown by molecular beam epitaxy

Thesis/Dissertation ·
OSTI ID:5673511

The properties of CdTe films grown by molecular beam epitaxy (MBE) in ultrahigh vacuum were studied. Homoepitaxial growth of CdTe on CdTe and heteroepitaxial growth of CdTe on Si, InSb, and sapphire were investigated. The structural, optical, and electrical properties were investigated for each film. A systematic variation of the Cd/Te vapor flux ratio during film growth allowed the preparation of a series of films whose resistivity varied more than eleven orders of magnitude through incorporation of excess Te. Stoichiometric CdTe films were obtained using a stoichiometric vapor flux. A systematic study of CdTe film growth on hydroplaned (111)A and (111)B CdTe was undertaken. X-ray diffraction, uv reflection, and transmission electron diffraction measurements were employed to evaluate the structural quality of the CdTe films. Selected area transmission electron microscopy was used to determine film dislocation line densities. An entirely different film growth morphology was observed on the (111)A versus (111)B substrate surfaces. Growth of high quality, low dislocation density, twin-free CdTe films was achieved on hydroplaned (111)A CdTe substrates. High quality epitaxy was obtained on each substrate material. CdTe was found to act as an efficient surface state passivation material for InSb. The first reported growth of cubic-phase CdTe on (111)Si was obtained during this study. Sharp cubic-phase epitaxy was also obtained for thick (approx.5 ..mu..m) CdTe films on (1210) and (0001) sapphire substrates. The films grown on (0001) sapphire were of such high quality that a preliminary study of In doping of CdTe by MBE was undertaken. Some of the CdTe:In films grown on (0001) sapphire during this study were found to have extremely good photoelectric properties and had some of the highest electron mobilities ever reported for CdTe films.

OSTI ID:
5673511
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English