Gallium(III) nitride

Chembox new
Name = Gallium(III) nitride
IUPACName = Gallium(III) nitride
OtherNames = None Listed.
Name =
Section1 = Chembox Identifiers
CASNo = 25617-97-4
Section2 = Chembox Properties
Formula = GaN
MolarMass = 83.7297 g/mol
Appearance = Yellow powder.
Density = 6.15 g/cm³, solid
Solubility = Reacts.
MeltingPt = >2500°C [http://dx.doi.org/10.1063/1.1772878 Harafuji, Tsuchiya and Kawamura, J. Appl. Phys. 96, 2501-2512 (September 1, 2004)]
BoilingPt = -
pKb = N/A
Section3 = Chembox Structure
CrystalStruct = Wurtzite, Zinc Blende, Rock Salt
Section7 = Chembox Hazards
EUClass = None listed.
RPhrases = R36, R37, R38, R43.
SPhrases = S24, S37.
FlashPt = Non-flammable.
Section8 = Chembox Related
OtherAnions = None listed.
OtherCations = None listed.
Function = bases
OtherFunctn = None listed.
OtherCpds = BN, InN, AlN, AlAs, InAs,

GaSb, AlGaAs, InGaAs,

GaAsP, GaAs, GaMe₃,

AsH₃, GaP

Gallium nitride (GalliumNitrogen) is a very hard material commonly used in bright LEDs since the 1990s.

The compound is a direct-bandgap semiconductor material of wurtzite crystal structure, with a wide (3.4 eV) band gap, used in optoelectronic, high-power and high-frequency devices. It is a binary group III/group V direct bandgap semiconductor. Its sensitivity to ionizing radiation is low (like other group III nitrides), making it a suitable material for solar cell arrays for satellites. Because GaN transistors can operate at much hotter temperatures and work at much higher voltages than GaAs transistors, they make ideal power amplifiers at microwave frequencies.

Physical properties

GaN is a very hard, mechanically stable material with large heat capacity.Isamu Akasaki and Hiroshi Amano, "Crystal Growth and Conductivity Control of Group III Nitride Semiconductors and Their Application to Short Wavelength Light Emitters", Jpn. J. Appl. Phys. Vol.36(1997) 5393-5408 doi|10.1143/JJAP.36.5393] In its pure form it resists cracking and can be deposited in thin film on sapphire or silicon carbide, despite the mismatch in their lattice constants. GaN can be doped with silicon (Si) or with oxygen [http://www.osti.gov/bridge/product.biblio.jsp?osti_id=434361 Information Bridge: DOE Scientific and Technical Information - - Document #434361 ] ] to N-type and with magnesium (Mg) to P-type,Hiroshi Amano, Masahiro Kito, Kazumasa Hiramatsu and Isamu Akasaki, "P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI)", Jpn. J. Appl. Phys. Vol. 28 (1989) L2112-L2114, doi|10.1143/JJAP.28.L2112] however the Si and Mg atoms change the way the GaN crystals grow, introducing tensile stresses and making them brittle.Shinji Terao, Motoaki Iwaya, Ryo Nakamura, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki, "Fracture of AlxGa1-xN/GaN Heterostructure —Compositional and Impurity Dependence—", Jpn. J. Appl. Phys. Vol. 40 (2001) L195-L197, doi|10.1143/JJAP.40.L195] Gallium nitride compounds also tend to have a high spatial defect frequency, on the order of a hundred million to ten billion defects per square centimeter. [ [http://www.lbl.gov/Science-Articles/Archive/blue-light-diodes.html lbl.gov, blue-light-diodes] ]

GaN-based parts are very sensitive to electrostatic discharge.Hajime Okumura, "Present Status and Future Prospect of Widegap Semiconductor High-Power Devices", Jpn. J. Appl. Phys. Vol. 45 (2006) 7565-7586, doi|10.1143/JJAP.45.7565]

Developments

High crystalline quality GaN can be obtained by low temperature deposited buffer layer technology. [Applied Physics Letters, Volume 48, Issue 5, pp. 353-355 [http://link.aip.org/link/?APL/48/353] ] This high crystalline quality GaN led to the discovery of p-type GaN, p-n junction blue/UV-LEDs and room-temperature stimulated emissionHiroshi Amano, Tsunemori Asahi and Isamu Akasaki, "Stimulated Emission Near Ultraviolet at Room Temperature from a GaN Film Grown on Sapphire by MOVPE Using an AlN Buffer Layer", Jpn. J. Appl. Phys. Vol. 29 (1990) L205-L206 doi|10.1143/JJAP.29.L205] (indispensable for laser action).Isamu Akasaki, Hiroshi Amano, Shigetoshi Sota, Hiromitsu Sakai, Toshiyuki Tanaka and Masayoshi Koike, "Stimulated Emission by Current Injection from an AlGaN/GaN/GaInN Quantum Well Device", Jpn. J. Appl. Phys. Vol.34(1995) L1517-L1519 doi|10.1143/JJAP.34.L1517] This has led to the commercialization of high-performance blue LEDs and long-lifetime violet-laser diodes (LDs), and to the development of nitride-based devices such as UV detectors and high-speed field-effect transistors.

High-brightness GaN light-emitting diodes (LEDs) completed the range of primary colors, and made applications such as daylight visible full-color LED displays, white LEDs and blue laser devices possible. The first GaN-based high-brightness LEDs were using a thin film of GaN deposited via MOCVD on sapphire. Other substrates used are zinc oxide, with lattice constant mismatch only 2%, and silicon carbide (SiC).

Group III nitride semiconductors are recognized as one of the most promising materials for fabricating optical devices in the visible short-wavelength and UV region. Potential markets for high-power/high-frequency devices based on GaN include microwave radio-frequency power amplifiers (such as used in high-speed wireless data transmission) and high-voltage switching devices for power grids. A potential mass-market application for GaN-based RF transistors is as the microwave source for microwave ovens, replacing the magnetrons currently used. The large band gap means that the performance of GaN transistors is maintained up to higher temperatures than silicon transistors.The first Gallium Nitride metal/oxide semiconductor field-effect transistor (GaN MOSFET) was experimentally demonstrated by Weixiao Huang of Rensselaer Polytechnic Institute in early 2008 [Rensselaer Polytechnic Institute (2008). Weixiao Huang. Retrieved May 14, 2008, from http://www.eng.rpi.edu/lemelson/finalist_Huang.cfm]

Applications

GaN, when doped with a suitable transition metal such as manganese, is a promising spintronics material (magnetic semiconductors).

Nanotubes of GaN are proposed for applications in nanoscale electronics, optoelectronics and biochemical-sensing applications [http://dx.doi.org/10.1038/nature01551 Goldberger et al, Nature 422, 599-602 (10 April 2003)] ]

A GaN-based blue laser diode is used in the Blu-ray disc technologies, and in devices such as the Sony PlayStation 3.

The mixture of GaN with In (InGaN) or Al (AlGaN) with a band gap dependent on ratio of In or Al to GaN allows to build light emitting diodes (LEDs) with colors that can go from red to blue.

ynthesis

GaN crystals can be grown from a molten Na/Ga melt held under 100atm pressure of N₂ at 750^oC. As Ga will not react with N₂ below 1000^oC the powder must be made from something more reactive, and is usually made in one of the following ways:

Ga + NH₃ -> GaN + 3/2H₂
Ga₂O₃ + NH₃ -> GaN + H₂O

afety and toxicity aspects

The toxicology of GaN has not been fully investigated. The dust is an irritant to skin, eyes and lungs. The environment, health and safety aspects of gallium nitride sources (such as trimethylgallium and ammonia) and industrial hygiene monitoring studies of MOVPE sources have been reported recently in a review. [Journal of Crystal Growth (2004); doi|doi:10.1016/j.jcrysgro.2004.09.007]

ee also

* Schottky diode
* Semiconductor devices
* Molecular-beam epitaxy
* Epitaxy

References

Further reading

* Isamu Akasaki and Hiroshi Amano: "Breakthroughs in Improving Crystal Quality of GaN and Invention of the p–n Junction Blue-Light-Emitting Diode" Japanese Journal of Applied Physics, Vol. 45, No. 12, 2006, pp. 9001-9010.
*Isamu Akasaki and Hiroshi Amano: " Crystal Growth and Conductivity Control of Group III Nitride Semiconductors and Their Application to Short Wavelength Light Emitters" Japanese Journal of Applied Physics, Vol. 36, 1997, pp. 5393-5408.
* Shuji Nakamura, Gerhard Fasol, Stephen J. Pearton, "The Blue Laser Diode : The Complete Story", Springer; 2nd edition, October 2, 2000, (ISBN 3-540-66505-6)
* Jacques I. Pankove, T. D. Moustakas, "Gallium Nitride (GaN) II: Semiconductors and Semimetals", Academic Press, 1998 (ISBN 0-12-752166-6)
* [http://www.amazon.com/gp/product/3540665056/ Shuji Nakamura, Gerhard Fasol, Stephen J Pearton The Blue Laser Diode: The Complete Story, Springer Verlag, 2nd Edition (October 2, 2000)]
* [http://www.engineering.ucsb.edu/news/179/ UC Santa Barbara Professor Shuji Nakamura to receive Prince of Asturias Award.]

External links

Generic

* [http://mit.edu/tpalacios The Wide Bandgap Semiconductor Materials and Devices Group at MIT] .
* [http://www.msm.cam.ac.uk/GaN/ The Cambridge center for galium nitride (GaN)] .
* [http://www.tyndall.ie/gan Photonics Sources Group, Tyndall National Institute] GaN and other photonics research at the Tyndall National Institute, Ireland.
* [http://physchem.ox.ac.uk/MSDS/GA/gallium_nitride.html External MSDS Data Sheet] .
* [http://www.ioffe.rssi.ru/SVA/NSM/Semicond/GaN/index.html Ioffe data archive]
* [http://www.onr.navy.mil/sci_tech/31/312/ncsr/materials/gan.asp National Compound Semiconductor Roadmap] page at ONR
* [http://www.nitronex.com/index.html Nitronex] Nitronex is a corporation that is manufacturing GaN on silicon RF power transistors and GaN on silicon epi wafers for sale.
* [http://www.fbh-berlin.com/ Ferdinand-Braun-Institut für Höchstfrequenztechnik (FBH), Berlin] .

Commercial links

* [http://electronicmaterials.rohmhaas.com/products/default.asp?product=Trimethylgallium Informative commercial link to Trimethylgallium and other metalorganics.]
* [http://electronicmaterials.rohmhaas.com/businesses/micro/metalorganics/vapor.asp?caid=291 Interactive Vapor Pressure Chart for metalorganics] .