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Bandgap determination based on electrical quantum efficiency

: Helmers, H.; Karcher, C.; Bett, A.W.


Applied Physics Letters 103 (2013), No.3, Art. 032108, 3 pp.
ISSN: 0003-6951 (Print)
ISSN: 1077-3118
ISSN: 1931-9401 (online)
Bundesministerium für Bildung und Forschung BMBF
0327567A; KoMGen
Journal Article
Fraunhofer ISE ()
Materialien - Solarzellen und Technologie; III-V und Konzentrator-Photovoltaik; Alternative Photovoltaik-Technologien; III-V Epitaxie und Solarzellen; Solarzellen und Bauelemente; bandgap; efficiency; electroluminescence; temperature

A procedure to determine the bandgap of a semiconductor material from spectral electrical quantum efficiency measurements is presented. The procedure is based on the disorder-related exponential band tailing at energies below the bandgap, i.e., exponential onset of the absorption coefficient (often referred to as Urbach's rule). The procedure is applied to three materials, namely, Ga0.50In0.50P, Ga0.99In0.01As, and Ge, and the temperature-dependent bandgaps are derived for a temperature range of 278 to 443 K. The results are compared and validated with data from the literature and electroluminescence measurements.