부산대학교 도서관

$\hbox{In}_{x}\hbox{Ga}_{1 - x}\hbox{As}_{y}\hbox{Sb}_{1 - y}$ thermophotovoltaic (TPV) diodes were grown lattice matched to GaSb substrates by metal–organic vapor phase epitaxy in the bandgap range of $E_{G} = \hbox{0.5}$ to 0.6 eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density (PD) of $\eta_{\rm TPV} = \hbox{19.7}\%$ and $\hbox{PD} = \hbox{0.58}\ \hbox{W/cm}^{2}$, respectively, for a radiator temperature of $T_{\rm radiator} = \hbox{950}\ ^{\circ}\hbox{C}$, diode temperature of $T_{\rm diode} = \hbox{27}\ ^{\circ}\hbox{C}$, and diode bandgap of $E_{G} = \hbox{0.53}\ \hbox{eV}$. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters which for 0.53-eV InGaAsSb TPV energy conversion are $\eta_{\rm TPV} = \hbox{28}\%$ and $\hbox{PD} = \hbox{0.85}\ \hbox{W/cm}^{2}$ at the above operating temperatures. The most severe performance limits are imposed by 1) diode open-circuit voltage $(V_{\rm OC})$ limits due to intrinsic Auger recombination and 2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode $V_{\rm OC}$ is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance versus diode architecture indicates that $V_{\rm OC}$ and thus efficiency are limited by extrinsic recombination processes such as through bulk defects.