Hydrogen Passivation of Si and Be Dopants in InAlAs

ABSTRACTHydrogen passivation and thermal reactivation of Si donors and Be acceptors were investigated in In0.52Al0.48As grown by molecular beam epitaxy. The semiconducting alloy was passivated by exposure to monatomic hydrogen or deuterium from a remote microwave plasma. The passivation was achieved by exposing the samples to monatomic hydrogen at temperatures between 200 and 250 °C for 1h. The electrical activity of the dopants was monitored by spreading resistance and C-V measurements. The samples were homogeneously doped to concentrations of 1.5×1016 or 6×1017 Si / cm3 and 6×1017 Be / cm3. Both dopants were passivated by more than two orders of magnitude through the epitaxial layers. An additional annealing step (440°C, 5 min) resulted in a complete reactivation of the passivated dopants. In addition to the electrical measurements, secondary ion mass spectroscopy showed that for both the Be- and the Si-doped layers the hydrogen profiles were essentially identical to the dopant profiles throughout the epilayers. This behaviour suggests that hydrogen migration is a dopant-trapping-limited process in n-and p-type In0.52Al0.48As.