Effect of impurity trapping on the capacitance-voltage characteristics of n-GaAs/N-AlGaAs heterojunctions
- 10 February 1986
- journal article
- research article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 48 (6) , 428-430
- https://doi.org/10.1063/1.96520
Abstract
We have studied the capacitance‐voltage (C‐V) characteristics of Schottky barriers on inverted n‐GaAs/N‐AlGaAs and normal N‐AlGaAs/n‐GaAs heterojunctions. Impurities introduced during film growth produced a negative sheet charge of 6.0×1011 cm−2 at the interface of the inverted n‐GaAs/N‐AlGaAs heterojunction. The effectiveness of GaAs quantum wells in trapping these impurities was investigated. GaAs quantum wells 20 Å wide were placed in intervals of 2500 Å for the first 0.75 μm of the AlGaAs layer; in the last 0.25 μm, the periodicity of the quantum wells was progressively decreased by half with the last quantum well placed at about 160 Å from the GaAs/AlGaAs interface. The resulting measured interface charge concentration of 4.4×1010 cm−2 is more than a magnitude lower than measured before the use of the quantum wells and is essentially at the limit of the accuracy of the C‐V technique for this structure.Keywords
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