Semiconductor material growth

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. 

A schematic of epitaxial growth is shown in Fig. 2.11. As an example, it is possible to grow gallium arsenide epitaxially on silicon since the lattice parameters of the two materials are similar. On the other hand, deposition of indium phosphide on silicon is not possible since the lattice mismatch is 8%, which is too high. A solution is to use an intermediate buffer layer of gallium arsenide between the silicon and the indium phosphide. The lattice parameters of common semiconductor materials are shown in Fig. 2.12. 

Metallo-organic CVD (MOCVD) is a specialized area of CVD, which is a relatively newcomer, as its first reported use was in the 1960s for the deposition of indium phosphide and indium anti-monide. These early experiments demonstrated that deposition of critical semiconductor materials could be obtained at lower temperature than conventional thermal CVD and that epitaxial growth could be successfully achieved. The quality and complexity of the equipment and the diversity and purity of the precursor chemicals have steadily improved since then and MOCVD is now used on a large scale, particularly in semiconductor and opto-electronic applications.91P1... 

Conventional electrodeposition from solutions at ambient conditions results typically in the formation of low-grade product with respect to crystallinity, that is, layers with small particle size, largely because it is a low-temperature technique thereby minimizing grain growth. In most cases, the fabricated films are polycrystalline with a grain size typically between 10 and 1,000 nm. The extensive grain boundary networks in such polycrystalline materials may be detrimental to applications for instance, in semiconductor materials they increase resistivity... 

Having dealt with slow formation of the reacting anion, we now turn to the various mechanisms by which the CD compounds are formed. For the most part, the details of nucleation and film growth are left to the following section. Here we concentrate on the reactions taking place that form the semiconductor material. There are four main mechanisms for the compound formation, as outlined in Sec. 3.1 which one is operative depends on the specific process and reaction parameters. 

The many technological innovations in melt crystal growth of semiconductor materials all build on the two basic concepts of confined and meniscus-defined crystal growth. Examples of these two systems are shown schematically in Figure 1. Typical semiconductor materials grown by these and other methods are listed in Table I. The discussion in this section focuses on some of the design variables for each of these methods that affect the quality of the product crystal. The remainder of the chapter addresses the relationship between these issues and the transport processes in crystal growth systems. 

These measures of solute segregation are closely related to the spatial and temporal patterns of the flow in the melt. Most of the theories that will be discussed are appropriate for laminar convection of varying strength and spatial structure. Intense laminar convection is rarely seen in the low-Prandtl-number melts typical of semiconductor materials. Instead, nonlinear flow transitions usually lead to time-periodic and chaotic fluctuations in the velocity and temperature fields and induce melting and accelerated crystal growth on the typically short time scale (order of 1 s) of the fluctuations. 

Lawrence H. Dubois received his B.S. degree in chemistry from the Massachusetts Institute of Technology in 1976 and a Ph.D. in physical chemistry from the University of California, Berkeley, in 1980. Dubois then joined AT T Bell Laboratories in Murray Hill, NJ, to pursue studies of the chemistry and physics of metal, semiconductor, and insulator surfaces chemisorption and catalysis by materials formed at the metal-semiconductor interface and novel methods of materials growth and preparation. 

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