Growth of group III nitrides by metalorganic molecular beam epitaxy

Abstract

This paper will review the status of materials growth by metalorganic molecular beam epitaxy (MOMBE). Growth in the ultrahigh vacuum (UHV) environment of MOMBE offers many advantages, including the ability to grow ternary materials with high concentrations of indium. Good crystal quality can in fact be obtained for both InGaN and InAlN by optimizing the growth conditions, though those alloys containing Al are in general of higher quality and have smoother surface morphologies. Although UHV growth offers the advantage of lower growth temperatures and hence higher In mole fractions, it suffers from the need to use very low growth rates in order to obtain acceptable crystallinity. This paper will also discuss possible causes for this behavior and the feasibility of overcoming this limitation through the use of novel sources. This paper will conclude with a discussion on doping during growth by MOMBE and the prospects for improving hole concentrations through the use of carbon.