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The crystal quality of 0.3-µm-thick as-grown epitaxial silicon-on-sapphire (SOS) was improved using solid-phase epitaxy (SPE) by implantation with silicon to 1015ions/cm2at 175 keV and rapid annealing using electron-beam heating, n-channel and p-channel transistor mobilities increased by 31 and 19 percent, respectively, and a reduction in ring-oscillator stage delay confirmed that crystal defects near the upper silicon surface had been removed. Leakage in n-channel transistors was not significantly affected by the regrowth process but for p-channel transistors back-channel leakage was considerably greater than for the control devices. This is attributed to aluminum released by damage to the sapphire during silicon implantation.
Date of Publication: Sep 1985