Electronic and mechanical properties of Ge films grown on glass substrates

As germanium is closed lattice matched to GaAs, it is a suitable substrate for epitaxial growth. In the quest for inexpensive substrates, thin-film Ge grown on glass is an attractive candidate if suitable grain growth can be achieved. Here the authors will describe Ge films that are deposited by an...

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Bibliographic Details
Main Authors: Ahrenkiel, R.K., Ahrenkiel, S.P., Al-Jassim, M.M., Venkatasubramanian, R.
Format: Book
Language:English
Subjects:
ANTIMONY
CARRIER LIFETIME
CRYSTAL STRUCTURE
ENERGY BEAM DEPOSITION
EXPERIMENTAL DATA
GALLIUM ARSENIDE SOLAR CELLS
GERMANIUM
MATERIALS SCIENCE
SOLAR ENERGY
SPECTRAL RESPONSE
SUBSTRATES
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Summary:As germanium is closed lattice matched to GaAs, it is a suitable substrate for epitaxial growth. In the quest for inexpensive substrates, thin-film Ge grown on glass is an attractive candidate if suitable grain growth can be achieved. Here the authors will describe Ge films that are deposited by an e-beam evaporator on glass and are approximately 2000 {angstrom} thick. The films were annealed at 500 C and 600 C to improve the quality of the material. The growth was done in three steps with 1000 {angstrom} of Ge, 70 {angstrom} of Sb, and followed by another 1000 {angstrom} of Ge. Sb is an n-type dopant in Ge and is included to enhance grain growth. The best films contained the Sb layer and hole concentrations between 1.4 {times} 10{sup 15} to 1.6 {times} 10{sup 17} cm{sup {minus}3}. The largest hole mobility measured was 30.6 cm{sup 2}/Vs in the 1.4 {times} 10{sup 15} p-type sample. The electron lifetime was measured by ultra-high frequency photoconductive decay and the best lifetimes were in the 30- to 40-ns range. Scanning-electron microscope and transmission-electron microscope studies indicated a polycrystalline grain structure with grain size comparable to the film thickness.
ISSN:0160-8371