Ion damage build-up and amorphization was investigated, at liquid N temperatures in multi-layers with various compositions and structures, by using Rutherford back-scattering channelling and cross-sectional transmission electron microscopy. It was found that, in this multi-layer system, damage accumulated preferentially in the GaAs layers. However, the presence of AlGaAs enhanced the dynamic annealing process in adjacent GaAs regions. Therefore, amorphization was retarded close to the GaAs/AlGaAs interfaces; even when such regions suffered most collisional displacements. This dynamic annealing in AlGaAs, and at GaAs/AlGaAs interfaces, became more efficient with increasing Al content. However, the dynamic annealing process was not perfect and an amorphous phase could form at the interface at above a critical defect level or ion dose. When an amorphous phase nucleated, amorphization proceeded rapidly into the adjacent AlGaAs. This was explained in terms of an interplay between defect migration and defect trapping at an amorphous/crystalline or GaAs/AlGaAs interface. In addition, enhanced recrystallization of amorphous GaAs at the interface could occur during heating if an amorphous phase did not form in the adjacent AlGaAs layer. It was suggested that this was probably the result of mobile defects that were injected from the AlGaAs layer during heating.

H.H.Tan, C.Jagadish, J.S.Williams, J.Zou, D.J.H.Cockayne: Journal of Applied Physics, 1996, 80[5], 2691-701