Boron segregation to extended defects induced by self-ion implantation into siliconCarrier lifetime measurements have been used to characterize residual defects after low-energy implanting of silicon ions followed by high-temperature annealing ͑900 or 1000°C͒. The implant was found to result in two distinct regions of lifetime-reducing damage. First, a high recombination region, most likely due to stable dislocation loops, remained near the surface. In addition, deeply propagated defects, which were not present prior to annealing, were also detected. These deep defects, which are possibly silicon interstitials, diffuse so rapidly during annealing that their distribution becomes effectively uniform to a depth of 100 microns. Annealing at higher temperatures was found to reduce the severity of both the surface and the deeply propagated defects.

We have used capacitance–voltage and deep level transient spectroscopy techniques to study the relocation of impurities, such as Zn and Cu, in impurity-free disordered (IFD) p-type GaAs. A four-fold increase in the doping concentration is observed after annealing at 925 °C. Two electrically active defects HA (EV+0.39 eV) and HB2 (EV+0.54 eV), which we have attributed to Cu- and Asi/AsGa-related levels, respectively, are observed in the disordered p-GaAs layers. The injection of gallium vacancies causes segregation of Zn dopant atoms and Cu towards the surface of IFD samples. The atomic relocation process is critically assessed in terms of the application of IFD to the band gap engineering of doped GaAs-based heterostructures.

Arsenic antisite defects in p -GaAs grown by metal-organic chemical-vapor deposition and the EL2 defectThe effect of stress on defect creation and diffusion during impurity-free disordering of SiO x -capped n-GaAs epitaxial layers has been investigated using deep level transient spectroscopy. The oxygen content in the SiO x layer and the nature of the stress that it imposes on the GaAs layer were varied by changing the nitrous oxide flow rate, N, during plasma-enhanced chemical vapor deposition of the capping layer. The peak intensity of defects S1 and S4 increased with the increasing nitrous oxide flow rate to exhibit a maximum in the range 80 sccmϽNϽ200 sccm. Any further increase in N resulted in a decrease in peak defect intensity, which reached an almost constant value for N Ͼ350 sccm. On the other hand, the peak intensity of S2* increased linearly with N. We have explained the maximum in the intensity of defects S1 and S4 for 80 sccmϽNϽ200 sccm to be due to a corresponding maximum in the compressive stress which is experienced by the capped GaAs layer during annealing. Although the creation of S2*, which we have proposed to be a complex involving the gallium vacancy (V Ga ), is enhanced with the increasing compressive stress, it also becomes efficiently converted into the arsenic-antisite, As Ga . The compound effect of these opposing mechanisms results in a linear dependence of the peak intensity of S2* on N. This study is to the best of our knowledge the first to provide the evidence for the stress-dependent anti-correlation between V Ga -and As Ga -related defects in GaAs. We have also narrowed the origin of S1 to complexes involving arsenic interstitials, As i , and/or As Ga .