This paper reports on resistance and capacity measurements of ohmic contacts which were deposited on heteroepitaxially grown, Si-doped GaAs layers on Si substrates. It is observed that the process of rapid thermal annealing (RTA) considerably affects the ohmic properties of subsequently deposited contacts. With rising annealing temperature, the electrical resistivity in the GaAs layer and thus, the contact resistance increased essentially. Although the chemical concentration profile of Si dopants is not changed by RTA, the number of electrically active carriers is lowered. Photoluminescence measurements con&m that Si donors on Ga sites perform a site exchange to As vacancies, thereby forming Si acceptors. The extent of this exchange process is considerably enhanced by the presence of a high dislocation density in the heteroepitaxial GaAs films. 0 1995 American Institute of Physics.
Single-domain growth of a GaAs layer showing a relatively good crystal structure and specular surface has been demonstrated on a silicon substrate which has been cut along an exact (100) plane. The substrate was patterned with a sawtooth grating using electron beam lithography, and the layers were grown by molecular beam epitaxy.
Mechanical stress of thin GaAs layers on Si(100) was investigated by photo- and cathodoluminescence at 77 K and by x-ray diffraction. The thickness of the GaAs layers was varied between 1.3 and 3.3 μm. The mechanical stress was measured before and after a treatment by rapid thermal annealing (RTA) at a temperature of 930 °C. The results of these measurements show a significant increasing of stress on the 1.3 μm layer samples (30%) after RTA. A considerable improvement (50%) of the full width at half maximum of rocking curves on the 3.3 μm layer samples was observed. We have also observed a splitting of stress into two different values.
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