Bulk, liquid-encapsulated Czochralski GaAs may be reversibly changed from semiconducting (ρ~1 Ω cm) to semi-insulating (ρ~107 Ω cm) by slow or fast cooling, respectively, following a 5 h, 950°C soak in an evacuated quartz ampoule. This effect has been studied by temperature-dependent Han-effect, photoluminescence, infrared absorption, mass spectroscopy, and deep level transient spectroscopy measurements. Except for boron, the samples are very pure, with carbon and silicon concentrations less than 3 X 1014 cm-3. Donor and acceptor concentrations, on the other hand, are in the mid 1015 cm-3 range, which means that the compensation is primarily determined by native defects, not impurities. A tentative model includes a donor at Ec - 0.13 e V, attributed to VAs - AsGa , and an acceptor at Ev + 0.07 EV, attributed to VGa - GaAs
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Copyright © 1986, American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 49.17, and may be found at http://apl.aip.org/resource/1/applab/v49/i17/p1083_s1