Electron beam source molecular‐beam epitaxy of III–V compounds

A new technique for the growth of III–V compounds by molecular‐beam epitaxy has been developed which uses electron beam heating for evaporating the group III liquid metals. The growth chamber is vertical and incorporates three large capacity 40 cc hearths for Ga, Al, and In. The metal beam fluxes are measured and feedback controlled using a chopped ion gauge signal detection scheme. The beam signal is input to a Eurotherm 820 digital controller which regulates the e‐beam power supply and the control system is interfaced with an AT&T 3B2 computer. The dynamic response of the group III metal beam fluxes is very fast and well‐controlled. The beam fluxes can be changed by two orders of magnitude in <10 s without oscillation. The beam flux can be precisely tailored through the digital controller over a very wide range. This enables the growth of variable band gap III–V alloys with almost arbitrary composition. In addition, the system geometry provides excellent uniformity over large diameter wafers. This technique appears very attractive for production of III–V epilayers.