Materials Studies for Heterojunction Structures Grown by Metalorganic Chemical Vapor Deposition

摘要

The present program was structured to understand the limitations imposed by the use of an atmospheric pressure Metal Organic Chemical Vapor Deposition system on the growth of ultrathin abrupt heterostructure devices. During the course of the study a great deal of work that sheds light on this subject was published. As a result of these new findings and as a result of findings generated in this program a rather complete understanding of these limitations is now available. In particular we have investigated various aspects of reactor design to determine the role that they play in determining the ultimate capabilities of the process. We have also investigated the effect of growth interruption on the quality of heterojunctions and quantum wells and the role of transients generated by pressure and flow imbalances on the transient growth rate involved in the formation of ultrathin layers in an atmospheric pressure system. We have concluded that it is possible to grow high quality multiple quality multiple quantum well structures by MOCVD over a thickness range 20 A to 500 A when appropriate measures are taken to control imbalances in the system. We have shown that interruption of the growth poses no particular difficulty to the fabrication of quantum well structures and in fact there is an indication that it is an indication that it is beneficial. We are not at present able to shed any further light on the applicability of MOCVD to the fabrication of HEMT structures owing to the lack of an available domestic source of high purity trimethylgallium.