III-nitride InGaN-based solar cells have gained importance because their band gap can potentially cover most of the solar spectrum, spanning 0.7 eV to 3.4 eV. However, to use these materials to harvest additional energy, other properties such as their thermoelectric properties should be exploited. In this work, the Seebeck coefficient and the electrical conductivity of three InGaN alloys with various indium concentrations and Gd-doped GaN (GaN:Gd) were measured, and the power factor was calculated. We report a Seebeck value of $209 lV/K for Gd-doped GaN.

We report on a novel scheme of substrate engineering to obtain high-quality GaN layers on Si substrates. Ion implantation of an AlN∕Si substrate is performed to create a defective layer that partially isolates the III-nitride layer and the Si substrate and helps to reduce the strain in the film. Raman spectroscopy shows a substantial decrease in in-plane strain in GaN films grown on nitrogen implanted substrates. This is confirmed by the enhancement of the E2 (TO) phonon frequency from 564 to 567cm−1 corresponding to 84% stress reduction and substantial decrease in crack density for a 2-μm-thick GaN film. GaN films grown on implanted AlN∕Si substrate have better optical properties and smoother surface morphology as compared to nonimplanted AlN∕Si substrate.

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