Relationship between secondary defects and electrical activation in ion-implanted, rapidly annealed GaAs

The removal of lattice damage and consequent activation by rapid thermal annealing of implanted Si, Se, Zn, and Be in GaAs was investigated by capacitance-voltage profiling, Hall measurements, transmission electron microscopy (TEM), secondary ion mass spectrometry, and Rutherford backscattering. The lighter species show optimum electrical characteristics at lower annealing temperatures (∼850 °C for Be, ∼950 °C for Si) than the heavier species (∼900 °C for Zn, ∼1000 °C for Se), consistent with the amount of lattice damage remaining after annealing. TEM reveals the formation of high densities (107 cm−2) of dislocation loops after 800 °C, 3 s anneals of high dose (1×1015 cm−2) implanted GaAs, which are gradually reduced in density after higher temperature anneals (∼1000 °C). The remaining loops do not appear to affect the electrical activation or carrier mobility in the implanted layer, the latter being comparable to bulk values.