Smooth Surface Morphology and Long Carrier Lifetime of InGaP Realized by Low-Temperature-Grown Cover Layer

The growth of high-crystal-quality GaAs on InGaP without sacrificing the carrier lifetime and shunt resistance of the InGaP layer is reported, utilizing a 10 nm-thick low-temperature-grown InGaP cover layer (LTGCL). Electronic devices with a GaAs/InGaP heterostructure such as solar cells, high-electron-mobility transistors (HEMTs), and lasers have attracted considerable attention because of their superior characteristics compared with conventional homostructure devices. However, the device performance has scope for improvement, particularly, the interface quality. To realize high-performance GaAs/InGaP heterostructure devices, high-crystal-quality GaAs needs to be grown on high-temperature-grown InGaP, which has a long carrier lifetime and high shunt resistance. High-temperature-grown InGaP, however, has a rough surface, which degrades the crystal quality of the overlying GaAs. To solve this problem, the use of high-temperature-grown InGaP with an LTGCL is proposed, which has an atomic-scale smooth surface. The advantages of using an LTGCL are discussed with a heterostructure solar cell as an example. The findings of this study indicate that the LTGCL can contribute to further improvement of the performance of heterostructure devices.