Aluminium gallium antimonide
Aluminium gallium antimonide, also known as gallium aluminium antimonide or AlGaSb (AlxGa1-xSb), is a ternary III-V semiconductor compound. It can be considered as an alloy between aluminium antimonide and gallium antimonide. The alloy can contain any ratio between aluminium and gallium. AlGaSb refers generally to any composition of the alloy.
Preparation
AlGaSb films have been grown by molecular beam epitaxy, chemical beam epitaxy{{cite journal | vauthors=((Okuno, Y.)), ((Asahi, H.)), ((Kaneko, T.)), ((Itani, Y.)), ((Asami, K.)), ((Gonda, S.)) | journal=Journal of Crystal Growth | title=MOMBE growth of AlGaSb | volume=115 | issue=1–4 | pages=236–240 | date=1991 | doi=10.1016/0022-0248(91)90745-Q| bibcode=1991JCrGr.115..236O }} and liquid phase epitaxy{{cite journal | vauthors=((Wada, T.)), ((Kubota, K.)), ((Ikoma, T.)) | journal=Journal of Crystal Growth | title=Liquid phase epitaxial growth of AlGaSb | volume=66 | issue=3 | pages=493–500 | date=1984 | doi=10.1016/0022-0248(84)90147-7| bibcode=1984JCrGr..66..493W }} on gallium arsenide and gallium antimonide substrates. The result is a layered heterostructure on various III-V compounds.
Electronic properties
File:AlGaSb Bandgaps Room Temperature.png of AlGaSb on composition at room temperature (T = 300 K). Based on these recommended empirical relationships, the transition from a direct (Γ–Γ) to indirect (Γ–X) gap occurs at x = 0.43.]]
The bandgap and lattice constant of AlGaSb alloys are between those of pure AlSb (a = 0.614 nm, Eg = 1.62 eV) and GaSb (a = 0.610 nm, Eg = 0.73 eV).{{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 }} At an intermediate composition, the bandgap transitions from an indirect gap, like that of pure AlSb, to a direct gap, like that of pure GaSb. Different values of the composition at which this transition occurs have been reported over time, both from computational and experimental studies, with reported values ranging from x = 0.23 to x = 0.43.{{cite journal | vauthors=((Wang, F.)), ((Jia, Y.)), ((Li, S.-F.)), ((Sun, Q.)) | journal=Journal of Applied Physics | title=First-principles calculation of the 6.1 Å family bowing parameters and band offsets | volume=105 | issue=4 | pages=043101–043101–4 | date=2009 | doi=10.1063/1.3072688| bibcode=2009JAP...105d3101W }}{{cite journal | vauthors=((Mathieu, H.)), ((Auvergne, D.)), ((Merle, P.)), ((Rustagi, K. C.)) | journal=Physical Review B | title=Electronic energy levels in Ga1−xAlxSb alloys | volume=12 | issue=12 | pages=5846–5852 | date=1975 | doi=10.1103/PhysRevB.12.5846}} The spread in the reported values of the transition is mainly due to the closeness of the gap sizes at the Γ and L points in the Brillouin zone and variations in the experimentally-determined gap sizes.
Applications
AlGaSb has been incorporated into devices such as heterojunction bipolar and high-electron-mobility transistors,{{cite journal | vauthors=((Bennett, B. R.)), ((Khan, S. A.)), ((Boos, J. B.)), ((Papanicolaou, N. A.)), ((Kuznetsov, V. V.)) | journal=Journal of Electronic Materials | title=AlGaSb Buffer Layers for Sb-Based Transistors | volume=39 | issue=10 | pages=2196–2202 | date=2010 | doi=10.1007/s11664-010-1295-0| bibcode=2010JEMat..39.2196B | s2cid=54777000 }}{{cite journal | vauthors=((Bennett, B. R.)), ((Boos, J. B.)), ((Ancona, M. G.)), ((Papanicolaou, N. A.)), ((Cooke, G. A.)), ((Kheyrandish, H.)) | journal=Journal of Electronic Materials | title=InAlSb/InAs/AlGaSb Quantum Well Heterostructures for High-Electron-Mobility Transistors | volume=36 | issue=2 | pages=99–104 | date=2007 | doi=10.1007/s11664-006-0057-5| bibcode=2007JEMat..36...99B | s2cid=887524 }}{{cite journal | vauthors=((Furukawa, A.)), ((Mizuta, M.)) | journal=Electronics Letters | title=Heterojunction bipolar transistor utilising AlGaSb/GaSb alloy system | volume=24 | issue=22 | pages=1378–1380 | date= 1988 | doi=10.1049/el:19880943| bibcode=1988ElL....24.1378F }} resonant-tunneling diodes,{{cite journal | vauthors=((Magno, R.)), ((Bracker, A. S.)), ((Bennett, B. R.)) | journal=Journal of Applied Physics | title=Resonant interband tunnel diodes with AlGaSb barriers | volume=89 | issue=10 | pages=5791–5793 | date=2001 | doi=10.1063/1.1365940| bibcode=2001JAP....89.5791M }} solar cells,{{cite journal | vauthors=((Vadiee, E.)), ((Renteria, E.)), ((Zhang, C.)), ((Williams, J. J.)), ((Mansoori, A.)), ((Addamane, S.)), ((Balakrishnan, G.)), ((Honsberg, C. B.)) | journal=IEEE Journal of Photovoltaics | title=AlGaSb-Based Solar Cells Grown on GaAs: Structural Investigation and Device Performance | volume=7 | issue=6 | pages=1795–1801 | date=2017 | doi=10.1109/JPHOTOV.2017.2756056| doi-access=free }} short-wave infrared lasers,{{cite journal | vauthors=((Wang, C. A.)), ((Jensen, K. F.)), ((Jones, A. C.)), ((Choi, H. K.)) | journal=Applied Physics Letters | title=n -AlGaSb and GaSb/AlGaSb double-heterostructure lasers grown by organometallic vapor phase epitaxy | volume=68 | issue=3 | pages=400–402 | date=1996 | doi=10.1063/1.116698| bibcode=1996ApPhL..68..400W }} and a novel infrared light modulator.{{cite journal | vauthors=((Xie, H.)), ((Wang, W. I.)) | journal=Applied Physics Letters | title=Normal incidence infrared modulator using direct–indirect transitions in GaSb quantum wells | volume=63 | issue=6 | pages=776–778 | date=1993 | doi=10.1063/1.109904| bibcode=1993ApPhL..63..776X }} It is sometimes selected as an interlayer or buffer layer in studies of GaSb and InAs quantum wells.
Al-rich AlGaSb is sometimes selected over AlSb in heterostructures for being more chemically stable and resistant to oxidation than pure AlSb.
References
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{{Antimonides}}
{{Aluminium compounds}}
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{{Antimony compounds}}