InGaAsP solar cells grown by hydride vapor phase epitaxy

Abstract

Hydride vapor phase epitaxy (HVPE) has recently reemerged as a low-cost, high-throughput alternative to metalorganic chemical vapor deposition (MOCVD) for the growth of high-efficiency III-V solar cells. Quaternary InGaAsP solar cells in the bandgap range of ~1.7-1.8 eV are promising top-cell candidates for integration in Ill-V/Si tandem cells with projected one-sun efficiencies exceeding 30%. In this work, we report on the development of lattice-matched InGaAsP solar cells grown on GaAs substrates via HVPE at very high growth rates of ~ 0.7 μm/min. We demonstrate prototype 1.7 eV InGaAsP solar cells with an open-circuit voltage of 1.11 V. The short-circuit current is limited by the lack of a window layer in these early stage devices. The photo response of 1.7 InGaAsP solar cell with ~1.1 μm thick base layer is found to be nearly insensitive to variation in p-type base doping concentration in the range from N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> - 4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> to - 1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , indicating an effective carrier collection length on the order of - 1.1 μm or higher in our devices. These initial InGaAsP cell results are encouraging and highlight the viability of HVPE to produce mixed arsenide-phosphide solar cells grown lattice-matched on GaAs.