Multichamber Reactors : A Solution to the Problem of Graded Heterointerfaces in Hot-Wall Vpe Systems

Abstract

The "hydride" growth process is well established as a technique for producing high quality homoepitaxial layers of the common III-V binary materials. However, it is difficult to obtain abrupt heterointerfaces for example between Ga In As and In P, as the gas speed is generally slow in order for the gas to follow the desired temperature profile in its passage through the source to substrate. Thus under normal conditions, a change of composition will occur in a time corresponding to the growth of several thousands of angströms of material. This paper describes the growth of abrupt heterojunctions which have been achieved in a new geometry reactor, based on four separate growth chambers. In each chamber, the gas flow conditions for the growth of a specific composition are stabilised and changes of composition are achieved by rapidly moving the sample from one chamber to another. This new reactor has allowed us to grow multiple heterojunctions with an interface abruptness of better than 150 Å