Ion Implantation Disorder in Strained-Layer Superlattices

Abstract

AbstractCantilever-beam bending and RBS channeling measurements have been used to examine implantation-induced disorder and stress buildup in In0.2Ga0.8As/GaAs SLS structures. Implantation fluences from 1011 to 1015/cm2 were used for 150 keV Si, 320 keV Kr, and 250 keV Zn in SLS and GaAs bulk materials. The critical fluence for saturation of compressive stress occurs prior to amorphous layer formation and is followed by stress relief. For all the ions the maximum ion induced stress scales with energy density into atomic processes and stress relief occurs above ∼1 × 1020: keV/cm3. Stress relief is more pronounced for the SLSs than for bulk GaAs. We suggest that stress-relief may lead to slip or other forms of inelastic material flow in SLSs, which would be undesirable for active regions in device applications. Such material flow may be avoided by limiting maximum fluences or by multiplestep implantation and annealing cycles (or hot implants) at high fluences.