Organometallic molecular precursors for low-temperature MOCVD of III-V semiconductors

摘要

Metallorganic chemical vapor deposition is a practical technique for the preparation of III-V epitaxial layers used in the fabrication of microelectronic and optoelectronic devices. The usual Ga and As sources for GaAS epitaxy are Ga(CH$-3$/)$-3$/ and AsH$-3$/, respectively. However, the use of these precursors has some disadvantages related to the toxicity and storage of arsine, stoichiometry control problems, carbon incorporation and unwanted side reactions. Several groups of researchers have investigated alternative sources of both the group III and group V elements. A review of these new organometallic precursors is presented in this paper. However, because group III and group V elements form Lewis acid-base adducts in the CVD reactor, we have investigated the attractive idea of using this class of compounds as single starting material. Several adducts have been successfully used for epitaxial growth of GaAs. Moreover, to avoid loss of stoichiometry due to dissociation of the adduct, the ability of organometallic molecules which feature a covalent bond between the group III and group V elements has also been investigated. These covalent compounds are probably formed in the MOCVD reactor using alkyl group V compounds containing acidic hydrogen R$- 3$MIN@n$/MH$-n$/ (M $EQ As, P; n $EQ 1.2). These new precursors are also briefly reviewed.