Planarizing HVPE Growth on GaAs Substrates Produced by Controlled Spalling

In this work, we show hydride vapor phase epitaxy (HVPE) overgrowth behavior of two growth conditions on three different facet morphologies produced by controlled spalling of (100) GaAs. In situ planarization of the surface through overgrowth has potential to overcome the significant challenge facets present to direct regrowth of photovoltaic devices and enabling low-cost substrate reuse. Substrate offcut and spall depth affect the surface morphology of the facet face, and this morphology plays an important role in facilitating planarizing overgrowth. We also show that growth conditions can be tuned to improve planarization efficiency on different surfaces. These results are critical for understanding the kinetics that allow planarizing growth to enable direct reuse of spalled (100) GaAs substrates.