Optoelectronics, Theory and Defect Physics of Zn-IV Nitride Semiconductors

ZnSn$_{\mathrm{x}}$Ge$_{\mathrm{1-x}}$N$_{\mathrm{2}}$ alloys with optical band gaps ranging from 2-3.1eV can be tuned to span a large portion of the solar spectrum, and could therefore be a viable earth-abundant light absorber and replacement for InGaN in nitride optoelectronic devices. They exhibit local order as demonstrated via X-ray absorption fine structure spectroscopy (EXAFS) and a linear relationship between the (002) peak position and composition in XRD studies. The bowing parameter is 0.29 eV for the measured band gaps of ZnSn$_{\mathrm{1-x}}$Ge$_{\mathrm{x}}$N$_{\mathrm{2}}$, significantly smaller than that of In$_{\mathrm{1-x}}$Ga$_{\mathrm{x}}$N, indicating that the ZnSn$_{\mathrm{1-x}}$Ge$_{\mathrm{x}}$N$_{\mathrm{2}}$ alloy band gaps can be tuned almost linearly by controlling the Sn/Ge composition. In this presentation we show theoretical studies of the optoelectronic behavior and defect physics of Zn(Sn,Ge)N$_{\mathrm{2\thinspace }}$series and experimental investigations via X-ray absorption and emission spectroscopy to probe the conduction and valence-band partial density of states. Band structure calculations from different methods will be shown in comparison with the experimental optical properties. Resonant inelastic scattering studies of the Zn(Sn,Ge)N$_{\mathrm{2}}$ lattice will be presented with their carrier dynamics obtained from pump-probe spectroscopy.