Decrease in the binding energy of donors in heavily doped GaN:Si layers |
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Authors: | I. V. Osinnykh K. S. Zhuravlev T. V. Malin B. Ya. Ber D. Yu. Kazantsev |
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Affiliation: | 1. Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia 2. Novosibirsk State University, Novosibirsk, 630090, Russia 3. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russia
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Abstract: | The properties of Si-doped GaN layers grown by molecular-beam epitaxy from ammonia are studied by photoluminescence spectroscopy. It is shown that the low-temperature photoluminescence is due to the recombination of excitons bound to donors at Si-atom concentrations below 1019 cm?3. At a Si-atom concentration of 1.6 × 1019 cm?3, the band of free excitons is dominant in the photoluminescence spectrum; in more heavily doped layers, the interband recombination band is dominant. A reduction in the binding energy of exciton-donor complexes with increasing doping level is observed. With the use of Haynes rule, whereby the binding energy of the complex in GaN is 0.2 of the donor ionization energy E D , it is shown that E D decreases with increasing Si concentration. This effect is described by the dependence {ie1134-1}, where E D otp is the ionization energy of an individual Si atom in GaN. The coefficient that describes a decrease in the depth of the impurity-band edge with increasing Si concentration is found to be α = 8.4 × 10?6 meV cm?1. |
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