Cathodoluminescence studies of anomalous ion implantation defect introduction in lightly and heavily doped liquid phase epitaxial GaAs:Sn

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Abstract
The anomalous postrange defect introduction produced by shallow ion implantation in GaAs has been investigated in Sn‐doped liquid phase epitaxial (LPE) material using depth‐resolved cathodoluminescence in conjunction with layer removal by chemical etching. 100‐keV Ne+ or 200‐keV Zn+ ions were implanted into lightly or heavily Sn‐doped LPE layers at temperatures between 80 and 300 K. All implantations were subsequently annealed at 300 K. Although the projected ion ranges for the implants were on the order of 1000 Å, significant postrange damage was observed at far greater depths. At depths up to several microns, the damage introduction produced severe nonradiative recombination but simultaneously caused an apparent increase in the concentration of incumbent luminescence centers responsible for an extrinsic band near 1.39 eV. A weak damage‐related band near 1.2 eV could also be seen in one instance. At depths of 5–30 μm, the postrange damage had the opposite effect of annihilating incumbent 1.39‐eV luminescence centers. The efficiency of the damage introduction has a complicated temperature dependence which is significantly different for the ion/substrate combinations investigated. However, no conditions were found for which the damage introduction could be inhibited. While our measurements are the most extensive to date concerning the anomalous ion implant damage introduction in GaAs, the detailed mechanisms responsible for this effect still remain obscure owing in part to the limited understanding of defects in GaAs.