The silicon doping characteristics of AlxGa1−xN were investigated over the x=0.2–0.5 composition range. A combination of Hall and capacitance–voltage measurements indicated a significant deepening of the Si level, as well as a systematic increase in carrier compensation with increasing compositions. Optical isothermal capacitance transient spectroscopy also revealed the presence of two midgap states with concentrations in the low 1017 cm−3 range. The two levels, which are thought to be responsible for the observed compensation, have been assigned to the third and second ionization states of the aluminum vacancy.

Articles you may be interested inEffect of doping on the mid-infrared intersubband absorption in GaN/AlGaN superlattices grown on Si(111) templates Appl.Transport and photoluminescence of silicon-doped GaInP grown by a valved phosphorus cracker cell in solid source molecular beam epitaxyThe properties of Si-doped Al 0.23 Ga 0.77 N grown by metalorganic vapor-phase epitaxy have been investigated by photoluminescence and Hall effect measurements. Nonintentionally doped samples were found to be insulating, while the room temperature carrier concentration of the doped layers did not vary linearly with the silane flow. The Si donor activation energy decreases with the doping level and the results correlate very well with those of Si-doped GaN. The temperature dependence of the photoluminescence spectra of the samples, in particular, their quenching with increasing temperature, can be explained by considering characteristic energies deduced from the Hall effect measurements. Our study shows that Al 0.23 Ga 0.77 N is a well-behaved semiconductor alloy, in which Si is a standard hydrogeniclike donor.

We report on the characterization of ZnO thin films grown by metal organic chemical vapor deposition (MOCVD) using diethyl zinc (DEZ) and tert-butanol (TBOH) as precursors. Substrate temperature proved to be a crucial factor in the crystallization process, as it vastly impacted the structural properties of the samples studied. Highly c-axis oriented films with large grain size (52 nm), low tensile strain (0.6%), uniform substrate coverage and a columnar structure devoid of hexagonal needles were successfully deposited on n-Si (100) substrates. The temperature-dependent luminescence spectra recorded confirmed the excellent quality of the material obtained in this work. Our results so far set TBOH apart as an outstanding oxygen source for the MOCVD growth of ZnO.

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The properties of undoped and Si-doped Al x Ga 1−x N layers grown by metalorganic vapour-phase epitaxy have been investigated by photoluminescence and Hall effect measurements. The variable temperature photoluminescence properties of the layers were typical of Al x Ga 1−x N, with the temperature dependence of the peak energy showing the often-observed S-shape. The low and variable temperature photoluminescence properties of undoped material could be well described using alloy potential fluctuation theory. However, this was not the case for moderately Si-doped material, for which much larger S-shape behaviour, and thus larger exciton localization, was observed for samples with x > 0.3. The temperature dependence of the PL peak intensity of the Si-doped Al x Ga 1−x N layers, as well as their Hall activation energies, were then studied in order to obtain possible origins for the large increase in the exciton localization energy. It is tentatively proposed that the increase in the exciton localization could be related to the 9 → 7 valence band crossover, which occurs at roughly the same composition (0.2 < x < 0.3).