1080 nm InGaAs laser power converters grown by MOCVD using InAlGaAs metamorphic buffer layers

Metamorphic InGaAs laser power converters have a great potential to be used for a delivery of electrical energy over distances of centimeters up to kilometers. The direct band gap InGaAs material covers monochromatic wavelengths around 1100 nm, which can be supplied by widespread commercial lasers. In this study, the InGaAs-based laser power converter have been designed to absorb a laser at 1080 nm and grown by metalorganic chemical vapor deposition. Step graded InAlGaAs buffer layers were employed to overcome the lattice mismatch problem between InGaAs and GaAs. Various epitaxial growth conditions such as overshoot layer which contains higher indium composition than the final buffer layer, back surface field barrier, growth temperature and V/III ratio were studied to obtain high quality InAlGaAs metamorphic buffer. The fabricated InGaAs-based laser power converter, which had an enhanced metamorphic buffer and 5 μm thick grid metal, showed a high external quantum efficiency of 82.16% at 1080 nm wavelength. As a result, a conversion efficiency of 37.87% was achieved under 1080 nm monochromatic light at a laser power density of 538 mW/cm2. Further improvements are expected when the device structure is modified to reduce the series resistance and the growth condition is optimized to increase the minority carrier life time.