  High performance thermoelectric materials for wide-range temperature
applications still remains a challenge. In this study, we have produced
high-quality homogeneous $In_{0.32}Ga_{0.68}N$ on ZnO substrates, with no phase
separation at high Indium content, using metal organic chemical vapor
deposition for thermoelectric applications. A record high room temperature
figure of merit zT is obtained of 0.86, which is five times larger than that of
SiGe, the current state of the art high temperature thermoelectric material.
These materials are shown to have a nearly perfect doping concentration to
maximize zT regardless of the scattering mechanism. This almost one order of
magnitude increase in zT is due to large electrical conductivities from oxygen
co-doping as well as low thermal conductivities from alloy scattering. The
maximum power factor reached was $77.98x10^{-4} W/mK^{2}$ at 300K for
$In_{0.32}Ga_{0.68}N$ alloys at a carrier concentration $~6.25x10^{20}
cm^{-3}$. This work indicates that $In_{x}Ga_{1-x}N$ alloys have great
potential for thermoelectric applications especially at a high temperature
range.
