Deep-level transient spectroscopy studies of Ni- and Zn-diffused vapor-phase-epitaxy n-GaAs

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Abstract
Nickel diffused into VPE n‐GaAs at 700 °C for 20 min reduces the hole diffusion length Lp from 4.3 to 1.1 μm. Deep‐level transient spectroscopy (DLTS) has been used to identify energy levels in Ni‐diffused GaAs at Ev+0.39 eV and Ec−0.39 eV, which have identical concentration profiles. The as‐grown VPE GaAs contains traces of these levels as well as an electron trap at Ec−0.75 eV in a concentration of 1.5×1015 cm−3. Ni diffusion reduces the concentration of this level by an amount that matches the increase in concentration of each of the two Ni‐related levels. Previous work has shown that the Ec−0.75 eV level is related to growth under As‐rich conditions, so it may be a gallium vacancy complex. A technique for measuring minority‐carrier capture cross sections has been developed, and indicates that Lp in Ni‐diffused VPE n‐GaAs is controlled by the Ec−0.39 eV level.