The Chemistry and Growth of MOVPE-Based Selective Epitaxy

Abstract

The expansion of device and materials concepts over the last decade was a result of the accurate and controlled growth of epitaxial materials whose composition can be modulated on the monolayer level in the growth direction. Selective area growth extends this dimensional control during growth from a typically planar conformal deposition to the achievement of an arbitrary lateral definition down to the sub-micron level. This structural control in three dimensions leads to new materials, physical structures, and devices. Selective epitaxy will form a key element in the development of advanced electric and opto-electronic devices and establishes the basis for an integrated materials technology for detector applications. The achievement of a selective epitaxy technology requires the determination of the surface chemistry important for selective deposition, the identification of alternative growth precursors, surface modification to enhance the selectivity and finally the development of useful models of the selective growth process incorporating chemically-based findings. The development of selective epitaxial techniques have centered on the use of conventional precursors such as trimethyl gallium in combination with AsH3. Halogen-based growth chemistries have offered an alternative growth chemistry for achieving selective epitaxy. Recently, the development of new precursors, such as diethyl gallium chloride, or the use of conventional precursors in conjunction with HC1 or AsCl3 have offered greater flexibility in the development of a selective area epitaxial process.