Compound Semiconductors and Crystal Growth Tec
A key component in semiconductor microtechnology is the production and quality control of the basic semiconductor materials from which devices and integrated circuits are made. These semiconductor materials are usually composed of single crystals of high perfection and high purity.
Today, silicon technology has reached the stage where complex integrated circuits containing millions of transistors can be manufactured reproducibly and reliably. This is not only a result of the development of device technology, but also the improvement of base material quality. For example, the silicon material that is now used for devices has an impurity concentration less than one part in ten billion. Unlike silicon, compound semiconductors consist of at least two different types of atoms. Compound semiconductors are emerging as important materials suitable for optoelectronic applications, which involve the optical and electrical properties of the semiconductors. Gallium Arsenide is an example of a compound semiconductor material. Although its technology is not yet as mature as the one of silicon, there is currently much effort being done in order to achieve a very high circuit operational speed as a consequence of the high electron mobility in this material.
When improving the technology for a particular semiconductor material, a specific range of issues must be resolved before high performance devices can be fabricated with a high degree of reproducibility and reliability. Only then can large-scale production be contemplated. An important consideration in this process, which will decide whether a material or technology will be commercially used, is the costs of implementation and production. To establish a new material technology or fabrication technique, it is essential to demonstrate that a significantly improved performance, lower costs and/or new device functionalities will result.
In this Chapter, we will first review the properties of major III-V compound semiconductors. We will then describe the current techniques used in the synthesis of semiconductor crystals. These are divided into two categories: single crystal growth techniques and epitaxial growth techniques. The former is used to fabricate semiconductor crystals of macroscopic size that will be processed into substrates, while the latter is used to deposit thin films of a few micrometers (or less) onto one of these substrates.
KeywordsBandgap Energy Molecular Beam Epitaxy Compound Semiconductor Seed Crystal Metalorganic Chemical Vapor Deposition
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