Pressure-dependent measurement on n+GaAs (Si, Sn): The effect of deep donor (DX) states on the electrical properties and presistent photoconductivity effects
Abstract
Shubnikov-de Haas measurements up to magnetic fields of 20 T are used to study the effects of hydrostatic pressure on the free electron concentration (n) and mobility (mu) of MBE-grown n(+)GaAs layers heavily doped with either Si or Sn. This type of layer forms the electrical contacts to a variety of (AlGa)As/GaAs tunneling devices and superlattices that were investigated under hydrostatic pressure. Increasing the pressure from zero causes an immediate and large decrease of n and increase of mu in n(+) samples doped at 1.8 x 10 to the 19th/cu cm. Illumination with red light at low temperatures (40 K) leads to a persistent restoration of n to its zero pressure level. This is accompanied by a decrease in mu. It is concluded that the trap involved is a deep donor with DX character, present in the n(+)GaAs layers, at concentrations comparable to the doping level. It was found that the energy of the level relative to the L-minima decreases with increasing doping and that its pressure coefficient is close to that of the L-minima. At doping levels above 1.8 x 10 to the 19th/cu cm, the level is partially occupied even at atmospheric pressure. The properties of the deep donor level appear to be very similar for both Si-and Sn-doping. Examples of how these DX centers affect the current-voltage characteristics of tunneling devices as a function of hydrostatic pressure are given.
- Publication:
-
Superlattices, Microstructures and Microdevices
- Pub Date:
- 1987
- Bibcode:
- 1987smm..conf...36P
- Keywords:
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- Electrical Properties;
- Electron Tunneling;
- Gallium Arsenides;
- Hydrostatic Pressure;
- Photoconductivity;
- Doped Crystals;
- Electron Density (Concentration);
- Electron Mobility;
- Pressure Dependence;
- Pressure Measurement;
- Solid-State Physics