MOCVD process

This article focuses primarily on the properties of the most extensively studied III—V and II—VI compound semiconductors and is presented in five sections (/) a brief summary of the physical (mechanical and electrical) properties of the 2incblende cubic semiconductors (2) a description of the metal organic chemical vapor deposition (MOCVD) process. MOCVD is the preferred technology for the commercial growth of most heteroepitaxial semiconductor material (J) the physics and (4) apphcations of electronic and photonic devices and (5) the fabrication process technology in use to create both electronic and photonic devices and circuits. 

Later on, this concept was extended to precursors containing both elements of the desired material already connected by a chemical bond in a single molecule. Such precursors are mainly referred to as single source precursors. Their potential application for the deposition of thin films of the corresponding binary materials by MOCVD processes could be demonstrated. In particular Lewis acid-base adducts R3M—ER3 and four- and six-membered heterocycles [R2MER x (Fig- 1) have been in the focus of research groups both in industry and university. Consequently, the development of powerful synthetic pathways for the preparation of such precursors has been forced. 

Most semi-conducting zinc compounds, such as the chalcogenides ZnS and ZnSe, are made from simple organozinc compounds and volatile sources of chalcogens, such as H2S and H2Se. Because of the enormous economic importance of these solid-state materials, these MOCVD processes are among the major consumers of organozinc compounds. 

This review has described the synthesis, structure and reactivity of important classes of group 13/15 compounds such as Lewis acid base adducts and heterocycles. In addition, their potential to serve as single source precursors for the deposition of the corresponding binary materials by MOCVD process has been demonstrated. Because of the large number of compounds containing the lighter elements of group 15, N, P and As, these... 

Nomura, R. Sekl, Y. Matsuda, H. 1992. Preparation of copper indium sulfide (CuInS2) thin films by single-source MOCVD process using Bu2In(SPr)Cu(S2CNPrj)./. Mater. Chem. 2 765-766. 

Ill—V and III—VI material films,380-384 which exhibit potential applications in opto- and micro-electronic devices, by MOCVD processes has led to the synthesis of novel heteroatomic complexes including the heavier elements of groups 15 (Sb, Bi) and 16 (Se, Te). These have been only scarcely known before, but are now available due to the exploration of novel synthetic strategies. 

Abstract The review summarizes recent studies on the synthesis of M - Sb compounds and their potential application to serve as single-source precursor in MOCVD processes. General reaction pathways for the synthesis of simple Lewis acid-base adducts R3M - ER 3 and heterocycles of the type [R2MSbR 2]x (M = Al, Ga, In) are described. As-formed compounds were studied in detail in MOCVD processes using hot-wall and cold-wall reactors. Advantages as well as problems using single-source precursors are described. 

As-described compounds have also been proposed to be formed as intermediates in the gas phase in the traditional two-component MOCVD process (pre-reactions). For instance, the deposition of AlN from AlMe3 and NH3 [11] most likely proceeds through a multistep-reaction mechanism including both the adduct Me3Al-NH3 and the heterocycle [Me2AlNH2]3, that is formed after elimination of one equivalent of methane, as more or less stable reaction intermediates. This is supported by the fact that both compounds have been successfully used for the deposition of AIN in the absence of any additional NH3 [12]. The same was found for the deposition of InP from InMe3 and PH3 [13]. 

The main advantage of as-described heterocycUc single-source precursors compared to Lewis acid-base adducts is, that these don t tend to give MSb whiskers. Unfortunately, their volatility is much lower and the MOCVD process has to be performed under high-vacuum conditions (10 -10 mbar). In addition, the precursor has to be heated up to 130 °C in order to ensure a reasonable precursor hux rate. 

The thermal decomposition of Cp substituted silicon compounds with the elimination of pentamethylcyclopentadiene (Cp I I) turns out to be synthetically very useful. As shown in equations 43-45, extreme conditions are necessary to selectively cleave the respective Si—C(Cp ) bond94-96. In this context, it is important to mention the use of cyclopentadienyl silicon compounds in the metalorganic chemical vapour deposition (MOCVD) process or in related techniques95,96. 

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