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Title:Carbon doping and hydrogen passivation in indium gallium arsenide and indium phosphide/indium gallium arsenide heterojunction bipolar transistors grown by metalorganic chemical vapor deposition
Author(s):Stockman, Stephen Andrew
Doctoral Committee Chair(s):Stillman, Gregory E.
Department / Program:Electrical and Computer Engineering
Discipline:Electrical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Electronics and Electrical
Physics, Condensed Matter
Engineering, Materials Science
Abstract:The development of carbon doping for producing stable p-type doping profiles in MOCVD-grown GaAs has made MOCVD the preferred technique for production of highly reliable GaAs-based HBT structures. In the InP/InGaAs materials system, however, inefficient C incorporation and amphoteric behavior have previously prevented the use of C as an intentional dopant, and redistribution problems associated with Zn prevent the use of MOCVD for growth of stable HBTs. This thesis describes recent work on carbon doping of GaAs, InGaAs, and InP, with emphasis placed on issues related to the use of C as the base dopant in InP/InGaAs HBTs.
The alloy composition of InGaAs was found to be affected by CCl$\sb4$ etching during growth. Etching can be reduced, and carbon incorporation can be greatly enhanced, by growing at low temperatures ($\rm T\sb{g}<550\sp\circ C).$ However, at these low temperatures the incorporation of Ga is controlled by surface kinetics. Substitution of TEGa for TMGa has resulted in improvements in uniformity and allowed growth at temperatures as low as $\rm T\sb{g}\sim450\sp\circ C,$ where a doping level of $\rm p\sim7\times10\sp{19}cm\sp{-3}$ has been achieved in $\rm In\sb{0.53}Ga\sb{0.47}As.$
The unintentional H passivation of C acceptors in InGaAs has been found to depend on the growth conditions and the post-growth cooling ambient. The incorporation of H and reversal of H passivation in the base of HBTs have been studied, and the dependence of majority and minority carrier transport properties on the degree of H passivation is also described. InP/InGaAs HBTs with a C-doped InGaAs base have been demonstrated, indicating that C is a well-behaved acceptor in InGaAs. Two issues currently limit further progress. The first is difficulty in controlling the InGaAs alloy composition. The second is passivation of C acceptors during growth of the base region of HBT structures, which limits the p-type doping level to less than $10\sp{19}$ cm$\sp{-3}.$
Finally, the use of C (from TMIn) as an n-type dopant in InP has been investigated. High C incorporation is obtained at low T$\sb{\rm g},$ but poor InP material quality degrades the performance of HBTs with a C-doped base and emitter. Intentional C-doping of InP using CCl$\sb4$ at low T$\sb{\rm g}$ results in growth of highly resistive material.
Issue Date:1993
Rights Information:Copyright 1993 Stockman, Stephen Andrew
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9543794
OCLC Identifier:(UMI)AAI9543794

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