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Encyclopedia of Physical Science and Technology EN009J-427 July 6, 2001 20:25

496 Metalorganic Chemical Vapor Deposition

Hydride A chemical compound containing only chemi- tors, and a variety of other electronic and optoelectronic
cal bonds between atoms of an element and hydrogen devices. This paper will review some of the important as-
atoms (e.g., AsH 3 ). pects of this technology.
Metalorganic A compound containing one or more
chemical bonds between a metal atom and the car-
bon atoms of an organic radical, e.g., (CH 3 ) 3 Ga; I. SUMMARY OF THE METALORGANIC
these compounds are also known as “metal alkyls” or CHEMICAL VAPOR DEPOSITION
“organometallics.” PROCESS
Precursor A chemical compound that is used as an “in-
put” to a chemical process to produce a desired product. A. Nomenclature
Precursors are often referred to as “sources.”
Pressure In most CVD processes, the pressures are de- Over the years since 1968, there have been several other
scribed relative to “standard atmospheric pressure” names applied to this process, including metal-alkyl vapor
2
measured at the earth’s surface (∼14.7 lbs/in abso- phase epitaxy (MAVPE), metalorganic VPE (MOVPE),
lute or PSIA), equivalent to 760 Torr, 1000 mbar, or organometallic CVD (OMCVD), and organometallic VPE
100 kPa. (OMVPE). However, Manasevit first used the term “met-
Pyrolysis The decomposition of a compound using ther- alorganic” (emphasizing the metal component) because
mal energy. that was the common term applied to the “metal alkyl”
Pyrophoric A compound that reacts with air in a way that compounds at this time and “CVD” because he felt that
results in spontaneous ignition. the process could be broadly applied to “chemical vapor
III–V compound semiconductor A semiconductor that deposition” of many different materials, including poly-
in pure form is composed of a mixture of atoms of one crystalline and amorphous films—the term “vapor-phase
or more elements from Column III and an equal number epitaxy” is a special case of the more general term “chem-
of atoms of one or more elements from Column V of the ical vapor deposition.” Later, the term “organometallic”
Periodic Table. The Column III atoms are arranged on (emphasizing the organic component) came to be applied
one sublattice and the Column V atoms are on another. to these specific metal alkyl compounds by the synthetic
Vapor-phaseepitaxy(VPE) Anepitaxialgrowthprocess chemists studying these materials. This paper will use the
that only uses chemical precursors that are delivered to more “generic” and historical name “metalorganic chem-
the growing surface in the vapor-phase. ical vapor deposition” for this process.

B. Historical Development of MOCVD
METALORGANIC CHEMICAL VAPOR DEPOSI-
TION (MOCVD) is a process employing the pyrolysis of The MOCVD technology for the growth of III–V com-
vapor-phase mixtures of various chemical reagents (i.e., pound semiconductors has been extensively developed
precursors) to form thin solid films of materials as di- since its introduction, and has today become the dominant
verseasmetals,semiconductors,andinsulators.Currently, epitaxial materials technology for both research and pro-
the primary use of MOCVD is for the growth of crys- duction of III–V compound semiconductors. Because of
talline thin films of semiconductors and related materials. the flexibility in the growth process and the materials qual-
The application of MOCVD to the growth of the III–V ity of films produced by MOCVD, many important III–V
compound semiconductors will be the primary focus of devices have become commercially viable. The MOCVD
this article. The metalorganic chemical vapor deposition epitaxial growth technology as we know it today was first
technology has advanced remarkably since the first report reported in the scientific literature in early 1968 by H. M.
of the growth of semiconductor epitaxial films by H. M. Manasevit (North American Rockwell, United States).
Manasevit in 1968. The first high-performance semicon- However, prior to 1967, similar processes and experimen-
ductor devices realized by MOCVD were AlGaAs/GaAs tal results had been previously described in the patent
injection lasers and solar cells reported by R. D. Dupuis literature by other groups, e.g., T. R. Scott et al. (Stan-
et al. in 1977. In this past thirty-odd years, MOCVD has dard Telecommunications and Cables, United Kingdom),
been developed for the production of AlGaAs, InAlGaP, W. Miederer et al. (Siemens, West Germany), and R. A.
InGaAsP, InAlGaN, and a variety other III–V compound Ruehrwein (Monsanto, United States). In 1967, Manasevit
semiconductor materials. It is now the dominant technol- was primarily interested in technologies for the heteroepi-
ogy worldwide for the commercial production of light- taxial growth of III–Vs on insulating substrates, the ana-
emitting diodes, injection lasers, quantum-well lasers, logue of the silicon-on-insulator (SOI) and silicon-on-
solar cells, photodetectors, heterojunction bipolar transis- sapphire (SOS) technology that he had developed earlier.