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High crystalline quality GaN can be obtained by low temperature deposited buffer layer technology.<ref>{{cite journal| author =H. Amano et al.| title = Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer| url = http://link.aip.org/link/?APL/48/353|journal = Applied Physics Letters|volume = 48|year = 1986| page = 353| doi =10.1063/1.96549}}</ref> This high crystalline quality GaN led to the discovery of p-type GaN,<ref name=doi10.1143/JJAP.28.L2112 /> p-n junction blue/UV-[[LED]]s<ref name=doi10.1143/JJAP.28.L2112 /> and room-temperature stimulated emission<ref name=doi10.1143/JJAP.29.L205>{{cite journal| author = Hiroshi Amano, Tsunemori Asahi and Isamu Akasaki| title = Stimulated Emission Near Ultraviolet at Room Temperature from a GaN Film Grown on Sapphire by MOVPE Using an AlN Buffer Layer|journal = Jpn. J. Appl. Phys.|volume = 29|year = 1990|page = L205-L206|doi=10.1143/JJAP.29.L205}}</ref> (indispensable for laser action).<ref name=doi10.1143/JJAP.34.L1517>{{cite journal| author =Isamu Akasaki, Hiroshi Amano, Shigetoshi Sota, Hiromitsu Sakai, Toshiyuki Tanaka and Masayoshi Koike| title = Stimulated Emission by Current Injection from an AlGaN/GaN/GaInN Quantum Well Device| journal = Jpn. J. Appl. Phys.|volume = 34| year = 1995| page = L1517-L1519|doi =10.1143/JJAP.34.L1517}}</ref> This has led to the commercialization of high-performance blue LEDs and long-lifetime violet-laser diodes, and to the development of nitride-based devices such as UV detectors and high-speed [[field-effect transistor]]s.
High crystalline quality GaN can be obtained by low temperature deposited buffer layer technology.<ref>{{cite journal| author =H. Amano et al.| title = Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer| url = http://link.aip.org/link/?APL/48/353|journal = Applied Physics Letters|volume = 48|year = 1986| page = 353| doi =10.1063/1.96549}}</ref> This high crystalline quality GaN led to the discovery of p-type GaN,<ref name=doi10.1143/JJAP.28.L2112 /> p-n junction blue/UV-[[LED]]s<ref name=doi10.1143/JJAP.28.L2112 /> and room-temperature stimulated emission<ref name=doi10.1143/JJAP.29.L205>{{cite journal| author = Hiroshi Amano, Tsunemori Asahi and Isamu Akasaki| title = Stimulated Emission Near Ultraviolet at Room Temperature from a GaN Film Grown on Sapphire by MOVPE Using an AlN Buffer Layer|journal = Jpn. J. Appl. Phys.|volume = 29|year = 1990|page = L205-L206|doi=10.1143/JJAP.29.L205}}</ref> (indispensable for laser action).<ref name=doi10.1143/JJAP.34.L1517>{{cite journal| author =Isamu Akasaki, Hiroshi Amano, Shigetoshi Sota, Hiromitsu Sakai, Toshiyuki Tanaka and Masayoshi Koike| title = Stimulated Emission by Current Injection from an AlGaN/GaN/GaInN Quantum Well Device| journal = Jpn. J. Appl. Phys.|volume = 34| year = 1995| page = L1517-L1519|doi =10.1143/JJAP.34.L1517}}</ref> This has led to the commercialization of high-performance blue LEDs and long-lifetime violet-laser diodes, and to the development of nitride-based devices such as UV detectors and high-speed [[field-effect transistor]]s.


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).<ref name=review>{{cite journal| doi = 10.1063/1.358463| title = Large-band-gap SiC, III-V nitride, and II-VI ZnSe-based semiconductor device technologies| year = 1994| author = Morkoç, H.| journal = Journal of Applied Physics| volume = 76| pages = 1363}}</ref>
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).<ref name=review>{{cite journal| doi = 10.1063/1.358463| title = Large-band-gap SiC, III-V nitride, and II-VI ZnSe-based semiconductor device technologies| year = 1994| author = Morkoç, H.| journal = Journal of Applied Physics| volume = 76| pages = 1363}}</ref> Group III nitride semiconductors are in general recognized as one of the most promising semiconductor family for fabricating optical devices in the visible short-wavelength and UV region.


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 [[transistor]]s is as the microwave source for [[microwave oven]]s, replacing the [[magnetron]]s currently used. The large band gap means that the performance of GaN transistors is maintained up to higher temperatures than silicon transistors. First gallium nitride metal/oxide semiconductor field-effect transistors (GaN [[MOSFET]]) were experimentally demonstrated in 1993<ref>{{cite journal|doi = 10.1063/1.109549|title = Metal semiconductor field effect transistor based on single crystal GaN|year = 1993|author = Asif Khan, M.|journal = Applied Physics Letters|volume = 62|pages = 1786}}</ref> and they are being actively developed.
Very high breakdown voltages, high [[electron mobility]] and [[saturarion velocity]] of GaN has also made it an ideal candidate for high power and high temeperature microwave applications as evidenced by its impressive [[Johnson's figure of merit]]. 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 [[transistor]]s is as the microwave source for [[microwave oven]]s, replacing the [[magnetron]]s currently used. The large band gap means that the performance of GaN transistors is maintained up to higher temperatures than silicon transistors. First gallium nitride metal/oxide semiconductor field-effect transistors (GaN [[MOSFET]]) were experimentally demonstrated in 1993<ref>{{cite journal|doi = 10.1063/1.109549|title = Metal semiconductor field effect transistor based on single crystal GaN|year = 1993|author = Asif Khan, M.|journal = Applied Physics Letters|volume = 62|pages = 1786}}</ref> and they are being actively developed.


==Applications==
==Applications==

Revision as of 19:53, 11 May 2010

Gallium nitride
Names
IUPAC name
Gallium nitride
Identifiers
ECHA InfoCard 100.042.830 Edit this at Wikidata
RTECS number
  • LW9640000
Properties
GaN
Molar mass 83.73 g/mol
Appearance yellow powder
Density 6.15 g/cm3
Melting point >2500°C[1]
Reacts.
Band gap 3.4 eV (300 K, direct)
Electron mobility 440 cm2/(V·s) (300 K)
Thermal conductivity 1.3 W/(cm·K) (300 K)
2.429
Structure
Wurtzite
C6v4-P63mc
Tetrahedral
Hazards
Flash point Non-flammable.
Related compounds
Other anions
 Gallium phosphide
Gallium arsenide
Gallium antimonide
Other cations
 Boron nitride
Aluminium nitride
Indium nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Gallium nitride (Template:GalliumTemplate:Nitrogen) is a binary III/V direct bandgap semiconductor commonly used in bright light-emitting diodes since the 1990s. The compound is a very hard material that has a Wurtzite crystal structure. Its wide band gap of 3.4 eV affords it special properties for applications in optoelectronic, high-power and high-frequency devices. 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 gallium arsenide (GaAs) transistors, they make ideal power amplifiers at microwave frequencies.

Physical properties

GaN is a very hard, mechanically stable material with large heat capacity.[2] 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.[2] GaN can be doped with silicon (Si) or with oxygen[3] to N-type and with magnesium (Mg) to p-type;[4] however, the Si and Mg atoms change the way the GaN crystals grow, introducing tensile stresses and making them brittle.[5] 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.[6]

GaN-based parts are very sensitive to electrostatic discharge.[7]

Developments

High crystalline quality GaN can be obtained by low temperature deposited buffer layer technology.[8] This high crystalline quality GaN led to the discovery of p-type GaN,[4] p-n junction blue/UV-LEDs[4] and room-temperature stimulated emission[9] (indispensable for laser action).[10] This has led to the commercialization of high-performance blue LEDs and long-lifetime violet-laser diodes, 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).[11] Group III nitride semiconductors are in general recognized as one of the most promising semiconductor family for fabricating optical devices in the visible short-wavelength and UV region.

Very high breakdown voltages, high electron mobility and saturarion velocity of GaN has also made it an ideal candidate for high power and high temeperature microwave applications as evidenced by its impressive Johnson's figure of merit. 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. First gallium nitride metal/oxide semiconductor field-effect transistors (GaN MOSFET) were experimentally demonstrated in 1993[12] and they are being actively developed.

Applications

GaN, when doped with a suitable transition metal such as manganese, is a promising spintronics material (magnetic semiconductors). A GaN-based violet 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 the manufacture of light-emitting diodes (LEDs) with colors that can go from red to blue.[11]

Nanotubes of GaN are proposed for applications in nanoscale electronics, optoelectronics and biochemical-sensing applications[13]

GaN HEMTs have been offered commercially since 2006, and have found immediate home in various wireless infrastructure applications due to their high efficiency and high voltage operation. Second generation technology with shorter gate lengths will be addressing higher frequency telecom and aerospace applications.[citation needed]

Synthesis

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

2 Ga + 2 NH3 → 2 GaN + 3 H2
Ga2O3 + 2 NH3 → 2 GaN + 3 H2O

Safety

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.[14]

See also

References

  1. ^ T. Harafuji and J. Kawamura (2004). "Molecular dynamics simulation for evaluating melting point of wurtzite-type GaN crystal". Appl. Phys. 96: 2501. doi:10.1063/1.1772878.
  2. ^ a b Isamu Akasaki and Hiroshi Amano (1997). "Crystal Growth and Conductivity Control of Group III Nitride Semiconductors and Their Application to Short Wavelength Light Emitters". Jpn. J. Appl. Phys. 36: 5393–5408. doi:10.1143/JJAP.36.5393.
  3. ^ Information Bridge: DOE Scientific and Technical Information - Document #434361
  4. ^ a b c Hiroshi Amano, Masahiro Kito, Kazumasa Hiramatsu and Isamu Akasaki (1989). "P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI)". Jpn. J. Appl. Phys. 28: L2112-L2114. doi:10.1143/JJAP.28.L2112.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ Shinji Terao, Motoaki Iwaya, Ryo Nakamura, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki (2001). "Fracture of AlxGa1-xN/GaN Heterostructure —Compositional and Impurity Dependence". Jpn. J. Appl. Phys. 40: L195-L197. doi:10.1143/JJAP.40.L195.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ lbl.gov, blue-light-diodes
  7. ^ Hajime Okumura (2006). "Present Status and Future Prospect of Widegap Semiconductor High-Power Devices". Jpn. J. Appl. Phys. 45: 7565–7586. doi:10.1143/JJAP.45.7565.
  8. ^ H. Amano; et al. (1986). "Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer". Applied Physics Letters. 48: 353. doi:10.1063/1.96549. {{cite journal}}: Explicit use of et al. in: |author= (help)
  9. ^ Hiroshi Amano, Tsunemori Asahi and Isamu Akasaki (1990). "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. 29: L205-L206. doi:10.1143/JJAP.29.L205.
  10. ^ Isamu Akasaki, Hiroshi Amano, Shigetoshi Sota, Hiromitsu Sakai, Toshiyuki Tanaka and Masayoshi Koike (1995). "Stimulated Emission by Current Injection from an AlGaN/GaN/GaInN Quantum Well Device". Jpn. J. Appl. Phys. 34: L1517-L1519. doi:10.1143/JJAP.34.L1517.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ a b Morkoç, H. (1994). "Large-band-gap SiC, III-V nitride, and II-VI ZnSe-based semiconductor device technologies". Journal of Applied Physics. 76: 1363. doi:10.1063/1.358463.
  12. ^ Asif Khan, M. (1993). "Metal semiconductor field effect transistor based on single crystal GaN". Applied Physics Letters. 62: 1786. doi:10.1063/1.109549.
  13. ^ Goldberger; et al. (2003). "Single-crystal gallium nitride nanotubes". Nature. 422: 599–602. doi:10.1038/nature01551. {{cite journal}}: Explicit use of et al. in: |author= (help)
  14. ^ Shenaikhatkhate, D (2004). "Environment, health and safety issues for sources used in MOVPE growth of compound semiconductors". Journal of Crystal Growth. 272: 816. doi:10.1016/j.jcrysgro.2004.09.007.

Further reading

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