Measurement of MBE substrate temperature by photoluminescence

Abstract

Abstract A new method to measure the substrate temperature suitable for low-temperature growth MBE is presented, which utilizes photoluminescence from the substrate. Single optical fiber is used both to supply the excitation light from a laser to the substrate and also to gather the photoluminescence light from the substrate. An UHV flange with optical fiber feedthrough is used, which is bakable to a temperature 150°C and shows a negligible amount of vacuum leakage measured at a vacuum of 1 × 10 −9 torr. In the experiment a GaAs-AlAs MQW wafer was used for the substrate because of its narrow PL spectral width. Differences in substrate temperature between a large wafer and a small wafer and between before and after starting the growth were measured by this method.