Time-resolved photoluminescence investigations onHfO2-capped InP nanowires

Abstract

We have employed time-resolved photoluminescence (PL) spectroscopy to study the impact ofHfO2 surfacecapping by atomic layer deposition (ALD) on the optical properties of InP nanowires (NWs). The depositionof high-κ dielectrics acting as a gate oxide is of particular interest in view of possible applications ofsemiconductor NWs in future wrap-gated field effect transistors (FETs). A high number ofcharged states at the NW–dielectrics interface can strongly degrade the performance ofthe FET which explains the strong interest in high quality deposition of high-κ dielectrics. In the present work we show that time-resolved spectroscopyis a valuable and direct tool to monitor the surface quality ofHfO2-capped InP NWs. In particular, we have studied the impact of ALD process parametersas well as surface treatment prior to the oxide capping on the NW–dielectricsinterface quality. The best results in terms of the surface recombination velocity (S0 = 9.5 × 103 cm s − 1) were obtained for InP/GaP core/shell NWs in combination with a low temperature (100 °C) ALD process. While the present report focuses on the InP material system,our method of addressing the surface treatment for semiconductors with high-κ dielectrics will also be applicable to nanoelectronic devices based on other III/V materialsystems such as InAs.