Structural and electric properties of AlN substrates used for LED Heterostructures’ growth

Autor: T.Yu. Chemekova, S. S. Nagalyuk, Vladimir T. Bublik, I. A. Belogorokhov, Heikki Helava, N. B. Smirnov, A. V. Govorkov, K. D. Scherbatchev, A. Ya. Polyakov, Oleg Avdeev, E. N. Mokhov, Yu.N. Makarov
Rok vydání: 2011
Předmět:
Zdroj: Russian Microelectronics. 40:629-633
ISSN: 1608-3415
1063-7397
DOI: 10.1134/s1063739711080178
Popis: The structural characteristics and electrical properties of bulk aluminum nitride crystals grown by sublimation and used as substrates for light emitting diode (LED) structures and AlGaN/GaN field effect transistors were studied. The crystalline perfection was assessed by selective chemical etching and by X-ray diffraction techniques. Electrical and optical properties were investigated using the temperature dependence of conductivity, admittance spectroscopy, high-temperature/low-frequency capacitance voltage measurements and by photoinduced transient current spectroscopy (PICTS), microcathodoluminescence (MCL) spectra and MCL imaging techniques. It was established that the studied samples were single crystals with a large grain substructure, with characteristic grain size of several hundred microns and a dislocation density of 102–104 cm−2 inside the grains. The electrical characteristics of the crystals were governed by the compensation of residual donors with a level near Ec—0.3 eV by deep centers with activation energy of 0.7 eV, both centers manifesting themselves in the temperature dependence of conductivity and in admittance spectra. In addition, deep centers responsible for the luminescence band with the peak energy of 3.3 eV and associated with low-angle grain boundaries were also observed.
Databáze: OpenAIRE
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