Parameters of multilevel structure of the DX centre in GaAlAs from pressure studies of the Hall effect

Abstract
Thermal emission from resonant DX levels in Si-doped GaAlAs was studied by measuring the temperature evolution of free electron concentration. Pressure was used to fill the levels with electrons. The absolute numbers of electrons captured on individual DX levels (related to different local environments of relaxed Si centre) were determined as a function of pressure or temperature. The analysis of the data allows the authors to determine the parameters of three components of the DX multilevel system: emission energies, positions of the levels and their pressure and temperature variations. Their data support the double donor (negative-U) hypothesis. The contribution of individual levels in thermostimulated recovery of persistent photoconductivity was determined and their role in developing the step-like structure of this process explained.
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