Persistent photoconductivity in GaAsAlGaAs heterostructures measured by contactless corbino capacitance technique
✍ Scribed by O.P. Hansen; A. Kristensen; H. Bruus
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- English
- Weight
- 276 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
In the contactless
Corbino capacitance technique the heterostructure sample is placed flat on top of, and insulated from, the Corbino electrodes.
The electrical impedance of the Corbino sample assembly is measured at audio frequencies and at liquid Helium temperatures as a function of a dc magnetic field. The impedance versus magnetic field exhibits a Shubnikov-deHaas pattern from which the carrier density in the high mobility channel is extracted.
Illumination with a red light emitting diode is observed to increase the carrier density in a persistent and accumulative way. Due to the absence of contacts, the technique offers a possibility to test whether these are essential for carriers from photo excited DX centres in the AlGaAs to reach the high mobility channel.