Solid-phase epitaxy of AlxGa(1-x)As: kinetics as a function of composition

The solid-phase epitaxy (SPE) of amorphised Al_xGa/sub (1-x/)As alloys, with x=0-0.46, has been investigated at temperatures over the range 220-310°C. Samples were implanted with ⁷⁴Ge ions at 200 keV and then annealed. Time resolved reflectivity (TRR) and Rutherford backscattering spectrometry in combination with channeling (RBS/C) were used to deduce the recrystallisation kinetics as a function of Al content. Residual disorder was characterised with RBS/C and cross-sectional transmission electron microscopy (XTEM). The SPE rate exhibited an Arrhenius temperature dependence at all compositions. The activation energy (~1.60 eV) and the pre-exponential (on average 4.0×10¹⁵ Å/s) for the process varied little with composition. At all compositions, single crystal regrowth was observed over 200-400 Å followed by the onset of twinning. RBS/C minimum yield values, indicative of the twinned volume fraction, were ~0.90 independent of Al content