View source for Indium arsenide antimonide

{{Short description|Mineral alloy}}
'''Indium arsenide antimonide''', also known as '''indium antimonide arsenide''' or '''InAsSb''' ([[Indium|In]][[Arsenic|As]]<sub>1-x</sub>[[Antimony|Sb]]<sub>x</sub>), is a ternary [[III-V|III-V semiconductor]] compound. It can be considered as an alloy between [[indium arsenide]] (InAs) and [[indium antimonide]] (InSb). The alloy can contain any ratio between arsenic and antimony. InAsSb refers generally to any composition of the alloy.{{Citation needed|date=November 2024}}

== Preparation ==
InAsSb films have been grown by [[molecular beam epitaxy]] (MBE), [[metalorganic vapor phase epitaxy]] (MOVPE) and [[liquid phase epitaxy]] (LPE) on [[gallium arsenide]] and [[gallium antimonide]] substrates. It is often incorporated into layered heterostructures with other III-V compounds.{{Citation needed|date=November 2024}}

=== Thermodynamic stability ===
Between 524&nbsp;°C and 942&nbsp;°C (the melting points of pure InSb and InAs, respectively), InAsSb can exist at a two-phase liquid-solid equilibrium, depending on temperature and average composition of the alloy.<ref name="Rogalski2020">{{cite journal | vauthors=((Rogalski, A.)), ((Martyniuk, P.)), ((Kopytko, M.)), ((Madejczyk, P.)), ((Krishna, S.)) | journal=Sensors | title=InAsSb-Based Infrared Photodetectors: Thirty Years Later On | volume=20 | issue=24 | pages=7047 | date=2020 | doi=10.3390/s20247047| doi-access=free | pmid=33317004 | pmc=7763214 | bibcode=2020Senso..20.7047R }}</ref><ref name="Ishida1989">{{cite journal | vauthors=((Ishida, K.)), ((Nomura, T.)), ((Tokunaga, H.)), ((Ohtani, H.)), ((Nishizawa, T.)) | journal=Journal of the Less Common Metals | title=Miscibility gaps in the GaP-InP, GaP-GaSb, InP-InSn and InAs-InSb systems | volume=155 | issue=2 | pages=193–206 | date=1989 | doi=10.1016/0022-5088(89)90228-2}}</ref>

InAsSb possesses an additional [[miscibility gap]] at temperatures below approximately 503&nbsp;°C.<ref name="Ishida1989" /> This means that intermediate compositions of the alloy below this temperature are thermodynamically unstable and can spontaneously separate into two phases: one InAs-rich and one InSb-rich. This limits the compositions of InAsSb that can be obtained by near-equilibrium growth techniques, such as LPE, to those outside of the miscibility gap.<ref name="Rogalski2020" /> However, compositions of InAsSb within the miscibility gap can be obtained with non-equilibrium growth techniques, such as MBE and MOVPE. By carefully selecting the growth conditions and maintaining relatively low temperatures during and after growth, it is possible to obtain compositions of InAsSb within the miscibility gap that are [[Metastability|kinetically stable]].{{Citation needed|date=November 2024}}

== Electronic properties ==
{{multiple image
 | total_width = 450
 | image1 = InAsSb composition temperature bandgap 2D map.png
 | caption1 = InAsSb bandgap in [[electron volt]]s as a function of composition (x) and temperature ([[Kelvin|K]]).<ref name="Rogalski2020" />
 | height1 = 100
 | image2 = InAsSb composition bandgap at 300K and 77K.png
 | caption2 = InAsSb bandgap in electron volts as a function of composition (x) at 300 K (room temperature, blue line) and 77 K ([[liquid nitrogen]] temperature, red line).
 | height2 = 100
 }}
The [[bandgap]] and lattice constant of InAsSb alloys are between those of pure [[Indium arsenide|InAs]] (a = 0.606&nbsp;nm, E<sub>g</sub> = 0.35 [[electronvolt|eV]]) and [[Indium antimonide|InSb]] (a = 0.648&nbsp;nm, E<sub>g</sub> = 0.17 eV).<ref name="VMR">{{cite journal | vauthors=((Vurgaftman, I.)), ((Meyer, J. R.)), ((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 InAs and InSb. The direct bandgap displays strong bowing, reaching a minimum with respect to composition at approximately x = 0.62 at room temperature and lower temperatures. The following empirical relationship has been suggested for the direct bandgap of InAsSb in [[electron volt|eV]] as a function of composition (0 < x < 1) and temperature (in [[Kelvin]]):<ref name="Rogalski2020" />

<math>E_{g}(x,T) = 0.417 - (1.28\cdot 10^{-4})T - (2.6\cdot 10^{-7})T^{2} - x(C + 0.182 + (10^{-9})T^{2}) + x^{2}(C - (5.8\cdot 10^{-4}) + (10^{-7})T^{2})</math>

This equation is plotted in the figures, using a suggested bowing parameter of C = 0.75 eV. Slightly different relations have also been suggested for E<sub>g</sub> as a function of composition and temperature, depending on the material quality, strain, and defect density.{{Citation needed|date=November 2024}}

== Applications ==
Because of its small direct bandgap, InAsSb has been extensively studied over the last few decades, predominantly for use in [[Infrared#Regions|mid- to long-wave infrared]] [[photodetector]]s that operate at room temperature and cryogenic temperatures.<ref name="Rogalski2020" /> InAsSb is used as the active material in some commercially available infrared photodetectors. Depending on the [[heterostructure]] and detector configuration that is used, InAsSb-based detectors can operate at wavelengths ranging from approximately 2 μm to 11 μm.{{Citation needed|date=November 2024}}

== See also ==
* [[Mercury cadmium telluride]] - a ternary II-VI compound that has a widely tunable bandgap and is used in commercial mid- and long-wave infrared photodetectors.
* [[Aluminium arsenide antimonide]] - a ternary III-V compound that is used as a barrier material in some InAsSb-based photodetectors.

== References ==
{{reflist}}

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

{{Antimonides}}
{{Indium compounds}}
{{Arsenides}}
{{Antimony compounds}}

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