Heterojunction-induced phenomena in Hall effect and photoconductivity measurements of epitaxial AlxGa1−xAs
- 1 February 1983
- journal article
- research article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 54 (2), 857-861
- https://doi.org/10.1063/1.332048
Abstract
Temperature‐dependent Hall effect measurements are reported for n‐type, Si‐doped Al0.32Ga0.68As films grown on semi‐insulating GaAs substrates. Results are presented for films grown with and without undoped Al0.32Ga0.68As buffer layers. For T≥200 K, the free electron concentration in these Si‐doped films has an exponential dependence on temperature with an activation energy of ∼93 meV. The temperature‐independent free‐electron concentration observed for T≤100 K is due to conduction in the GaAs substrate near the substrate‐epilayer interface (i.e., a two‐dimensional electron gas). Hall mobilities measured in thin (≤5 μm) AlxGa1−xAs films, particularly at low temperatures, can be dominated by this conduction mechanism and are thus invalid as a measure of the transport properties of the AlxGa1−xAs films. In addition, photoconductivity data are presented which show that the persistent photoconductivity effect observed in these films is due primarily to charge separation at the AlxGa1−xAs/GaAs heterojunction.Keywords
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