Editing Gallium nitride (section)

== Physical properties ==
[[File:Crystal-GaN.jpg|thumb|left|GaN crystal]]

GaN is a very hard ([[Knoop hardness test|Knoop hardness]] 14.21&nbsp;GPa<ref name=GaNRZ>{{Cite web|url=http://web.eecs.umich.edu/~minar/pdf/GaN_review.pdf|title=Gallium Nitride as an Electromechanical Material. R-Z. IEEE 2014}}</ref>{{rp|4}}), mechanically stable [[wide-bandgap semiconductor]] material with high [[heat capacity]] and thermal conductivity.<ref name="doi10.1143/JJAP.36.5393">{{Cite journal | last1 = Akasaki | first1 = I. | last2 = Amano | first2 = H. | doi = 10.1143/JJAP.36.5393 | title = Crystal Growth and Conductivity Control of Group III Nitride Semiconductors and Their Application to Short Wavelength Light Emitters | journal = Japanese Journal of Applied Physics | volume = 36 | issue = 9A | pages = 5393 | year = 1997 |bibcode = 1997JaJAP..36.5393A | doi-access = free }}</ref> 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 constant]]s.<ref name="doi10.1143/JJAP.36.5393" /> GaN can be [[dopant|doped]] with [[silicon]] (Si) or with [[oxygen]]<ref name=ostidDE97001220 >Wetzel, C.; Suski, T.; Ager, J.W. III; Fischer, S.; Meyer, B.K.; Grzegory, I.; Porowski, S. (1996) [http://www.osti.gov/bridge/product.biblio.jsp?osti_id=434361 Strongly localized donor level in oxygen doped gallium nitride], International conference on physics of semiconductors, Berlin (Germany), 21–26 July 1996.</ref> to [[N-type semiconductor|n-type]] and with magnesium (Mg) to [[P-type semiconductor|p-type]].<ref name="doi10.1143/JJAP.28.L2112">{{Cite journal | last1 = Amano | first1 = H. | last2 = Kito | first2 = M. | last3 = Hiramatsu | first3 = K. | last4 = Akasaki | first4 = I. | title = P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI) | doi = 10.1143/JJAP.28.L2112 | journal = Japanese Journal of Applied Physics | volume = 28 | issue = 12 | pages = L2112 | year = 1989 |bibcode = 1989JaJAP..28L2112A | doi-access = free }}</ref><ref>{{Cite web |title=Discovery in gallium nitride a key enabler of energy efficient electronics |url=https://news.cornell.edu/stories/2019/09/discovery-gallium-nitride-key-enabler-energy-efficient-electronics |access-date=2022-10-20 |website=Cornell Chronicle |language=en}}</ref> However, the Si and Mg atoms change the way the GaN crystals grow, introducing [[tensile stress]]es and making them brittle.<ref name="doi10.1143/JJAP.40.L195">{{Cite journal | last1 = Terao | first1 = S. | last2 = Iwaya | first2 = M. | last3 = Nakamura | first3 = R. | last4 = Kamiyama | first4 = S. | last5 = Amano | first5 = H. | last6 = Akasaki | first6 = I. | doi = 10.1143/JJAP.40.L195 | title = Fracture of Al<sub>x</sub>Ga<sub>1−x</sub>N/GaN Heterostructure – Compositional and Impurity Dependence – | journal = Japanese Journal of Applied Physics | volume = 40 | issue = 3A | pages = L195 | year = 2001 | bibcode=2001JaJAP..40..195T| s2cid = 122191162 }}</ref> [[Gallium]] [[nitride]] compounds also tend to have a high [[dislocation]] density, on the order of 10<sup>8</sup> to 10<sup>10</sup> defects per square centimeter.<ref>Preuss, Paul (11 August 2000). [http://www.lbl.gov/Science-Articles/Archive/blue-light-diodes.html Blue Diode Research Hastens Day of Large-Scale Solid-State Light Sources] {{Webarchive|url=https://web.archive.org/web/20101025005330/http://www.lbl.gov/Science-Articles/Archive/blue-light-diodes.html |date=25 October 2010 }}. Berkeley Lab., lbl.gov.</ref>

The [[United States Army Research Laboratory|U.S. Army Research Laboratory]] (ARL) provided the first measurement of the high field electron [[velocity]] in GaN in 1999.<ref>{{cite journal |last1=Wraback |first1=M. |last2=Shen |first2=H. |last3=Carrano |first3=J.C. |last4=Collins |first4=C.J |last5=Campbell |first5=J.C. |last6=Dupuis |first6=R.D. |last7=Schurman |first7=M.J. |last8=Ferguson |first8=I.T. |title=Time-Resolved Electroabsorption Measurement of the electron velocity-field characteristic in GaN |journal=Applied Physics Letters |volume=76 |issue=9 |pages=1155–1157 |doi=10.1063/1.125968 |year=2000 |bibcode=2000ApPhL..76.1155W }}</ref> Scientists at ARL experimentally obtained a peak [[Steady state|steady-state]] velocity of {{val|1.9|e=7|u=cm/s}}, with a [[Transient state|transit]] time of 2.5 picoseconds, attained at an [[electric field]] of 225&nbsp;kV/cm. With this information, the [[electron mobility]] was calculated, thus providing data for the design of GaN devices.