Reliability of pulsed electron-beam-alloyed AuGe/Pt ohmic contacts on GaAs has been studied and compared with thermally alloyed contacts. Electron-beam-alloyed contacts have excellent surface morphology and low contact resistance, but are not as reliable as thermally alloyed contacts; the specific contact resistance deteriorates with thermal aging at 250 °C. The degradation is explained by the interdiffusion and compound formation in the metals during aging.

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Semi-insulating Cr-doped single-crystal GaAs samples were implanted at room temperature with 300-keV Si ions in the dose range of (0.17–2.0)×1015 cm−2 and were subsequently steady-state annealed at 900 and 950 °C for 30 min in a H2 ambient with a Si3N4 coating. Differential Hall measurements showed that an upper threshold of about 2×1018/cm3 exists for the free-electron concentration. The as-implanted atomic-Si profile measured by SIMS follows the theoretical prediction, but is altered during annealing. The Cr distribution also changes, and a band of dislocation loops ∼2–3 kÅ wide is revealed by cross-sectional TEM at a mean depth of Rp∼3 kÅ. Incomplete electrical activation of the Si is shown to be the primary cause for the effect.

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