Selective Epitaxy of Compound Semiconductors in MOVPE Growth: Growth, Modelling, and Applications
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SELECTIVE EPITAXY OF COMPOUND SEMICONDUCTORS IN MOVPE GROWTH: GROWTH, MODELLING, AND APPLICATIONS T.F.KUECH, M.GOORSKY, A.PALEVSKY, P.SOLOMON, AND M.A.TISCHLER IBM T..J.Watson Research Center, P.O.Box 218, Yorktown Heights, NY, 1059g
ABSTRACT
Selective cpitaxial growth during metal-organic vapor phase epitaxy (MOVPE) can be accomplished over a wide range of growth conditions through the usC of alternative growth precursors. We have used chlorine-containing growth precursors, such as diethyl gallium chloride, (C 2Hs)2GaCI, to selectively grow GaAs and AIGaj As. The growth process has been thermodynamically modelled in order to estimate relative growth rates and alloy composition. This model indicates that near the growth front the growth process is chemically similar to the inorganic-based growth of compound semiconductors. This growth technique has been applied to the growth of extremely low resistance ohmic contact structures and quantum well structures.
INTRODUCTION
Selective epitaxy is the localized growth of an epitaxial material typically within lithographically determined openings in a masking material. This growth technique adds versatility to the design of device structures by enabling the device designer to construct epitaxial structures outside of the constraints of a purely planar geometry. The localized growth on a substrate surface can eliminate process steps, provide added functionality to the structure, and allow the incorporation of the masking material into the device structure. Selective epitaxy (SE) can be accomplished in several growth systems. Silicon-based SE utilizes growth precursors such as SiH.2 CI 2, with or without HCI addition, to limit the Si deposition to openings in a SiO 2 masking layer[I-4]. Selective GaAs growth has been achieved in the inorganic-based growth techniques under conditions of low gas phase supersaturation [5-7]. These hot wall GaAs growth techniques rely on the formation of GaCI in a source region. GaCi, InCI and AICI are high temperature halides formed by the reaction of HCI or AsCI3 with GaAs or an elemental source. Supersaturation and growth is accomplished by the addition of AsH3 or through a temperature reduction. SE is attributed to several factors in these growth techniques. The presence of an etching reaction due to HCI in the growth ambient, the near equilibrium nature of the growth, and the low adsorption probability of the growth nutrient on the masking materials can all contribute to the SE process. Metal organic vapor phase epitaxy (MOVPE) has emerged as a versatile alternative to these inorganic-based growth techniques. MOVPE has the ability to grow a wide variety of semiconductor compounds including Al-based materials[8]. The controlled introduction of growth reactants, high switching speed gas panels, and the broad range of growth precursors has lead to the application of MOVPE to virtually all device structures. The most common MOVPE growth precursors are metal alkyls. These cornMat. Res. Soc. Symp. Proc. Vol. 198. @1990 Materials Research Societ
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