Metalorganic vapour phase epitaxy
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'''Metalorganic vapour phase epitaxy''' (MOVPE) is a [[chemical vapour deposition]] method of [[epitaxy|epitaxial growth]] of materials, especially [[compound semiconductor]]s from the surface reaction of [[organic compound]]s or [[metalorganics]] and metal hydrides containing the required [[chemical element]]s. For example, [[indium phosphide]] could be grown in a reactor on a substrate by introducing [[Trimethylindium]] ((CH<sub>3</sub>)<sub>3</sub>In) and [[phosphine]] (PH<sub>3</sub>). Alternative names for this process include '''[[organometallic]] vapour phase epitaxy''' ('''OMVPE'''), '''metalorganic chemical vapour deposition''' ('''MOCVD''') and '''organometallic chemical vapour deposition''' ('''OMCVD'''). Formation of the epitaxial layer occurs by final pyrolisis of the constituent chemicals at the substrate surface. In contrast to [[molecular beam epitaxy]] (MBE) the growth of [[crystals]] is by chemical reaction and not physical deposition. This takes place not in a [[vacuum]], but from the [[gas]] phase at moderate [[pressure]]s (2 to 100 k[[Pascal (unit)|Pa]]). As such this technique is preferred for the formation of devices incorporating thermodynamically [[Phases_of_matter#Metastable_phases|metastable]] alloys. It has become the dominant process for the manufacture of [[laser diodes]], [[solar cells]], and [[LEDs]].
[[Image:MOCVDprocess.jpg]]
==Reactor components==
*A reactor is a chamber made of a material that does not react with the chemicals being used. It must also withstand high temperatures. This chamber is composed by reactor walls, liner, a [[susceptor]], gas injection units, and temperature control units. Usually, the reactor walls are made from stainless steel or quartz. To prevent over heating, cooling water must be flowing through the channels within the reactor walls. Special [[glass]]es, such as quartz or ceramic, are often used as the liner in the reactor chamber between the reactor wall and the susceptor. A substrate sits on a ''susceptor'' which is at a controlled temperature. The susceptor is made from a material resistant to the metalorganic compounds used; [[graphite]] is sometimes used. For growing nitrides and related materials, a special coating on the graphite susceptor is necessary to prevent corrosion by ammonia (NH<sub>3</sub>) gas.
[[Image:GenericMOCVD.jpg]]
*Gas inlet and switching system. Gas is introduced via devices known as 'bubblers'. In a bubbler a carrier gas (usually [[nitrogen]] or [[hydrogen]]) is bubbled through the metalorganic [[liquid]], which picks up some metalorganic vapour and transports it to the reactor. The amount of metalorganic vapour transported depends on the rate of carrier gas flow and the bubbler [[temperature]]. Allowance must be made for saturated vapours.
*Pressure maintenance system
*Gas Exhaust and cleaning System. Toxic waste products must be converted to liquid or solid wastes for recycling (preferably) or disposal. Ideally processes will be designed to minimize the production of waste products.
==Organometallic precursors==
A non-exhaustive list of organometallic chemicals used to grow [[semiconductors]] by MOVPE.
*Aluminium
**[[Trimethylaluminium]] CAS 75-24-1
**[[Triethylaluminium]] CAS 97-93-8
* Gallium
** [[Trimethylgallium]] (TMG or TMGa)
** [[Triethylgallium]] (TEG or TEGa)
** [[Triisopropylgallium]] (TIPG or TIPGa) Ga(C<sub>3</sub>H<sub>7</sub>)<sub>3</sub>
* [[Indium]]
** [[Trimethylindium]] (TMI or TMIn)
** [[Triethylindium]] (TEI or TEIn)
** [http://en.wiktionary.org/wiki/DIPMeIn Di-isopropylmethylindium (DIPMeIn)]
* [[Germanium]]
** [[Isobutylgermane]] [http://en.wiktionary.org/wiki/IBGE (IBGe)]
** [[Dimethylamino germanium trichloride]] (DMAGeC)
* [[Nitrogen]]
** [[Phenyl hydrazine]]
** [[Dimethylhydrazine]]
**[[Ammonia]]
* [[Phosphorus]]
** [[Phosphine]]
** [[Tertiarybutyl phosphine]] (TBP)
* [[Arsenic]]
** [[Arsine]] AsH<sub>3</sub>
** [[Phenylarsine]]
** [[Tertiarybutyl arsine]] (TBAs)
* [[Antimony]]
** [[Trimethyl antimony]] (TMSb)
** [[Triethyl antimony]] (TESb)
** [[Stibine]] SbH<sub>3</sub>
* [[Cadmium]]
** [[Dimethyl cadmium]] (DMCd)
* [[Tellurium]]
** [[Dimethyl telluride]] (DMTe)
** [[Diethyl telluride]] (DETe)
** [http://en.wiktionary.org/wiki/DIPTe Di-isopropyl telluride (DIPTe)]
==Semiconductors grown by MOVPE==
===III-V semiconductors===
* [[Aluminium gallium arsenide|AlGaAs]]
* [[Aluminum gallium indium phosphide|AlGaInP]]
* [[Aluminium gallium nitride|AlGaN]]
* [[Aluminum gallium phosphide|AlGaP]]
* [[Gallium arsenide phosphide|GaAsP]]
* [[Gallium arsenide|GaAs]]
* [[Gallium nitride|GaN]]
* [[Gallium phosphide|GaP]]
* [[Indium aluminum arsenide|InAlAs]]
* [[Indium aluminum phosphide|InAlP]]
* [[Indium antimonide|InSb]]
* [[gallium indium aluminum arsenide|GaInAlAs]]
* [[gallium indium aluminum nitride|GaInAlN]]
* [[gallium indium arsenide nitride|GaInAsN]]
* [[gallium indium arsenide phosphide|GaInAsP]]
* [[gallium indium arsenide|GaInAs]]
* [[gallium indium nitride|GaInN]]
* [[gallium indium phosphide|GaInP]]
* [[Indium nitride|InN]]
* [[Indium phosphide|InP]]
===II-VI semiconductors===
* [[Zinc selenide]] (ZnSe)
* [[HgCdTe]]
* [[ZnO]]
* [[Zinc sulfide]] (ZnS)
===IV Semiconductors===
* [[Silicon|Si ]]
* Ge
* [[Strained silicon]]
===IV-V-VI Semiconductors===
* [[GeSbTe]]
==See also==
*[[Thin-film deposition]]
==External links==
===Academic===
*[http://www.movpe.umi2958.eu/ 14th European MOVPE in Metz, France]
*[http://www.semiconductor-today.com Semiconductor Today: Online resource covering compound semiconductors and advanced silicon materials and devices]
===Environment, Health and Safety===
*[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJ6-4DHWWFR-H&_user=10&_handle=V-WA-A-W-ABD-MsSAYWW-UUA-U-AAZCBAYVAE-AAZWYEEWAE-VBCUZVWD-ABD-U&_fmt=summary&_coverDate=12%2F10%2F2004&_rdoc=129&_orig=browse&_srch=%23toc%235302%232004%23997279998%23530941!&_cdi=5302&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f9705c90ce8d1b3a4a3d7eb3b776580a Environment, Health and Safety Aspects of Metalorganic Sources used in MOVPE Growth of Compound Semiconductors]: From ''Journal of Crystal Growth'' (2004).
[[Category:Chemical processes]]
[[Category:Semiconductor growth]]
[[Category:Thin film deposition]]
==Further reading==
Gerald B. Stringfellow (1999). ''Organometallic Vapor-Phase Epitaxy: Theory and Practice (2nd ed.).'' Academic Press (ISBN 0-12-673842-4).
Manijeh Razeghi (1995). ''The MOCVD Challenge: Volumes 1 and 2.'' Institute of Physics Publishing (ISBN 0-7503-0309-3).
[[de:Metallorganische Gasphasenepitaxie]]
[[ja:有機金属気相成長法]]
[[ru:Осаждение металлорганических соединений из газообразной фазы]]
[[zh:有机金属化学气相沉积法]]