{{Chembox |Section1={{Chembox Identifiers | index_label=GaAs<sub>0.5</sub>Sb<sub>0.5</sub> | StdInChI=1S/AsH2.2Ga.Sb.6H/h1H2;;;;;;;;; | StdInChIKey=MIEVXBWDYAIMDS-UHFFFAOYSA-N | SMILES = [Ga].[Ga].[As].[Sb] }} |Section2={{Chembox Properties }} |Section8={{Chembox Related | OtherCompounds = [[Gallium arsenide]]; [[Gallium antimonide]]; [[Gallium indium arsenide antimonide phosphide]] }} }} '''Gallium arsenide antimonide''', also known as '''gallium antimonide arsenide''' or '''GaAsSb''' ([[Gallium|Ga]][[Arsenic|As]]<sub>(1-''x'')</sub>[[Antimony|Sb]]<sub>''x''</sub>), is a ternary [[III-V|III-V semiconductor]] compound; ''x'' indicates the fractions of arsenic and antimony in the alloy. GaAsSb refers generally to any composition of the alloy. It is an alloy of [[gallium arsenide]] (GaAs) and [[gallium antimonide]] (GaSb).

== Preparation == GaAsSb films have been grown by [[molecular beam epitaxy]] (MBE), [[metalorganic vapor phase epitaxy]] (MOVPE) and [[liquid phase epitaxy]] (LPE) on [[gallium arsenide]], [[gallium antimonide]] and [[indium phosphide]] substrates. It is often incorporated into layered heterostructures with other III-V compounds.

=== Thermodynamic Stability === GaAsSb has a [[miscibility gap]] at temperatures below 751&nbsp;°C.<ref name="MOVPE1">{{cite journal |author=Cherng, M. J. |author2=Stringfellow, G. G. |author3=Cohen, R. M. | journal=Applied Physics Letters | title=Organometallic vapor phase epitaxial growth of GaAs<sub>0.5</sub>Sb<sub>0.5</sub> | volume=44 | issue=7 | pages=677–679 | date=1984 | doi=10.1063/1.94874| bibcode=1984ApPhL..44..677C }}</ref> This means that intermediate compositions of the alloy below this temperature are thermodynamically unstable and can spontaneously separate into two phases: one GaAs-rich and one GaSb-rich. This limits the compositions of GaAsSb that can be obtained by near-equilibrium growth techniques, such as LPE, to those outside of the miscibility gap.<ref>{{cite book |editor=Madelung, O. |editor2=Rössler, U. |editor3=Schulz, M. | date= 2002 | chapter=GaAs(1-x)Sb(x), physical properties | publisher=Springer-Verlag | series=Landolt-Börnstein - Group III Condensed Matter | volume=b | pages=1–13 | chapter-url=http://materials.springer.com/lb/docs/sm_lbs_978-3-540-31356-4_25 | doi=10.1007/10832182_25 | isbn=978-3-540-42876-3 | title= Group IV Elements, IV-IV and III-V Compounds. Part b - Electronic, Transport, Optical and Other Properties }}</ref> However, compositions of GaAsSb within the miscibility gap can be obtained with non-equilibrium growth techniques, such as MBE and MOVPE. By carefully selecting the growth conditions (e.g., the ratios of precursor gases in MOVPE) and maintaining relatively low temperatures during and after growth, it is possible to obtain compositions of GaAsSb within the miscibility gap that are [[Metastability|kinetically stable]]. For example, this makes it possible to grow GaAsSb with the composition GaAs<sub>0.51</sub>Sb<sub>0.49</sub>, which, while normally within the miscibility gap at typical growth temperatures, can exist as a kinetically stable alloy.<ref name="MOVPE1" /> This composition of GaAsSb is latticed matched to [[InP]] and is sometimes used in heterostructures grown on that substrate.

== Electronic Properties == [[File:GaAsSb composition bandgap at room temperature.png|right|thumb|200px|Direct bandgap versus composition for GaAsSb.<ref name="MOVPE1" />]] The [[bandgap]] and lattice constant of GaAsSb alloys are between those of pure GaAs (a = 0.565&nbsp;nm, E<sub>g</sub> = 1.42 [[electronvolt|eV]]) and GaSb (a = 0.610&nbsp;nm, E<sub>g</sub> = 0.73 eV).<ref name="VMR">{{cite journal |author=Vurgaftman, I. |author2=Meyer, J. R. |author3=Ram-Mohan, L. R. | journal=Journal of Applied Physics | title=Band parameters for III–V compound semiconductors and their alloys | volume=89 | issue=11 | pages=5815–5875 | date=2001 | doi=10.1063/1.1368156| bibcode=2001JAP....89.5815V }}</ref> Over all compositions, the band gap is [[Direct bandgap|direct]], like in GaAs and GaSb. Furthermore, the bandgap displays a minimum in composition at approximately x = 0.8 at T = 300 K, reaching a minimum value of E<sub>g</sub> = 0.67 eV, which is slightly below that of pure GaSb.<ref name="MOVPE1" />

== Applications == GaAsSb has been extensively studied for use in [[heterojunction bipolar transistor]]s.<ref>{{cite journal |author=Bolognesi, C. R. |author2=Dvorak, M. M. W. |author3=Yeo, P. |author4=Xu, X. G. |author5=Watkins, S. P. | journal=IEEE Transactions on Electron Devices | title=InP/GaAsSb/InP double HBTs: a new alternative for InP-based DHBTs | volume=48 | issue=11 | pages=2631–2639 | date=2001 | doi=10.1109/16.960389| bibcode=2001ITED...48.2631B }}</ref><ref>{{cite journal |author=Ikossi-Anastasiou, K. | journal=IEEE Transactions on Electron Devices | title=GaAsSb for heterojunction bipolar transistors | volume=40 | issue=5 | pages=878–884 | date=1993 | doi=10.1109/16.210193| bibcode=1993ITED...40..878I }}</ref> <!--- There are many, many more references for GaAsSb HBTs in the primary literature, for the interested reader. ---> It has also been lattice-matched with [[InGaAs]] on [[InP]] to create and study a [[two-dimensional electron gas]].<ref>{{cite journal |author=Detz, H. |author2=Silvano De Sousa, J. |author3=Leonhardt, H. |author4=Klang, P. |author5=Zederbauer, T. |author6=Andrews, A. M. |author7=Schrenk, W. |author8=Smoliner, J. |author9=Strasser, G. | journal=Journal of Vacuum Science & Technology B | title=InGaAs/GaAsSb based two-dimensional electron gases | volume=32 | issue=2 | article-number=02C104 | date=2014 | doi=10.1116/1.4863299| bibcode=2014JVSTB..32bC104D | doi-access=free }}</ref>

A GaAsSb/GaAs-based heterostructure was used to make a near-infrared [[photodiode]] with peak responsivity centered at 1.3&nbsp;μm.<ref>{{cite journal |author=Sun, X. |author2=Wang, S. |author3=Hsu, J. S. |author4=Sidhu, R. |author5=Zheng, X. G. |author6=Li, X. |author7=Campbell, J. C. |author8=Holmes, A. L. | journal=IEEE Journal of Selected Topics in Quantum Electronics | title=GaAsSb: a novel material for near infrared photodetectors on GaAs substrates | volume=8 | issue=4 | pages=817–822 | date=2002 | issn=1558-4542 | doi=10.1109/JSTQE.2002.800848| bibcode=2002IJSTQ...8..817S }}</ref>

GaAsSb can be incorporated into III-V–based [[multi-junction solar cell]]s to reduce the tunneling distance and increase the tunneling current between adjacent cells.<ref>{{Citation |author=Klem, J. F. |author2=Zolper, J. C. | year=1997 | title=Semiconductor tunnel junction with enhancement layer | url=https://patents.google.com/patent/US5679963/en | access-date=27 December 2023}}.</ref>

== References == {{reflist}}

== External links == * [https://www.ioffe.ru/SVA/NSM/Semicond/GaAsSb/ Properties of GaAsSb]

{{Antimonides}} {{Gallium compounds}} {{Arsenides}} {{Antimony compounds}}

[[Category:Antimonides]] [[Category:Arsenides]] [[Category:Gallium compounds]] [[Category:III-V compounds]]