The Effect of Isoelectronic In-Doping on the Structural and Optical Properties of (Al)GaN Grown by Metalorganic Vapor Phase Epitaxy

We have studied the effect of isoelectronic In-doping on the structural and optical properties of GaN and Al_0.05Ga_0.95N. The films were grown by atmospheric metalorganic vapor phase epitaxy at 950°C in H₂ or N₂ carrier gas (hereafter referred to as H₂-(Al)GaN and N₂-(Al)GaN, respectively) with a low-temperature deposited AlN buffer layer. With the technique, we were able to control the strain in the films. Indeed, with increasing trimethylindium flow, the strain in GaN decreased, and accordingly, the tilting and twisting components of the crystalline mosaicity were also decreased. The photoluminescence (PL) emission peak energy shifted in accordance with the strain in GaN. Strong enhancement of the excitonic PL intensity of In-doped GaN and AlGaN was observed. In all the samples, room temperature PL mapping for linewidth and peak wavelength showed that with the addition of In, the uniformity of the PL improved significantly.