Abstract
Reports the photocapacitance (PHCAP) measurement results at 20 K of Te-doped GaAs crystals, which were rapidly cooled after annealing under various arsenic vapour pressures. The Ec-0.485 eV and Ec-0.492 eV deep donors which are peculiar to Te-doped GaAs are considered to arise from the presence of arsenic vacancies (VAs) and the donor impurity Te. The level density of the Ec-0.485 eV and Ec-0.492 eV donors decreases monotonically with increasing arsenic vapour pressure. The deep donors, which are classified into Ec-0.717 eV and Ec-0.737 eV levels, are considered to be associated with arsenic interstitial atoms (IAs), and their level density increases monotonically with increasing arsenic vapour pressure PAs(GaAs). The Ec-0.72 eV deep donor is commonly seen in various n-GaAs bulk crystals with different dopant impurities. Good spectral correspondences between the results of PHCAP, deep-level transient spectroscopy and deep-level photoluminescence (PL) measurements are also presented. The PHCAP and PL measurements show that the Ec-0.72 eV onset may originate from the presence of a greater number of IAs with a more strained configuration than the so-called EL2 level.
Published Version
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