Compact metalorganic molecular-beam epitaxy growth system

Abstract

This article describes a compact growth system specifically designed for metalorganic molecular-beam epitaxy (MOMBE) of InP-based materials. The system is designed to take full advantage of the MOMBE method, in particular the premixing of the group III and V precursors, respectively, and the elimination of large solid effusion cells. The system uses a fixed sample heating stage which is designed for indium wafer mounting, up to a 2 in. diameter, on molybdenum blocks. Temperature control during growth is done with a thermocouple inserted directly into the sample block with a small charge of indium to provide intimate thermal contact. Sample loading is done vertically from above in order to load the sample in the growth position. The system is controlled by a personal computer, which also replaces all of the analog temperature and pressure controllers. Initial results on 2-in. diameter wafers indicate excellent uniformity of the composition, Δa/a=±2×10−4 for InGaAs, and photoluminescence, ±4.5 nm for InGaAsP, respectively. In addition, high-speed InGaAs/InP heterostructure bipolar transistors and charge injection transistors grown in this system have demonstrated fT’s of 125 and 73 GHz, respectively.