Controlled vapor-pressure heat-treatment effect on deep levels in liquid-encapsulated czochralski-grown GaP crystals |
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Authors: | T. J. Yu T. Tanno K. Suto J. Nishizawa |
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Affiliation: | (1) Sendai Research Center, Telecommunications Advancement Organization of Japan, 980-0845 Sendai, Japan;(2) Department of Materials Sciences, Tohoku University, 980-8579 Sendai, Japan;(3) Semiconductor Research Institute, 980-0862 Sendai, Japan |
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Abstract: | Photocapacitance (PHCAP) measurements have been carried out on GaP crystals grown by the liquid-encapsulated Czochralski (LEC) method with heat treatment under various phosphorus-vapor pressures at different temperatures. Electron traps of EC−1.1 eV, EC−1.6 eV, EC−1.9 eV, and a hole trap of EV+2.26 eV are mainly detected. The phosphorus-vapor pressure dependence of the EC−1.9 eV trap density and their diffusion behavior indicate that they are interstitial phosphorus atoms. The densities of both EC−1.1 eV and EC−1.6 eV traps are strongly dependent on the shallow impurity concentrations. Moreover, the density of EC−1.1 eV traps increases with increasing phosphorus-vapor pressure. From these results, we suggest that EC−1.1 eV traps are the complexes of shallow donors and antisite phosphorus atoms. Deep-level densities in GaP crystals after annealing at 860°C or 960°C for 60 min are decreased almost one order of magnitude lower than those in untreated substrate crystals, which should have occurred via out-diffusion of interstitial phosphorus atoms. However, such an effect is not prominent for 800°C treatment for 60 min. |
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Keywords: | GaP phosphorus-vapor pressure heat treatment photocapacitance interstitial atoms antisite atoms |
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