Gallium arsenide antimonide, also known as gallium antimonide arsenide or GaAsSb (GaAs(1-x)Sbx), is a ternary 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).
GaAsSb has a miscibility gap at temperatures below 751 °C.[1] 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.[2] 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 kinetically stable. For example, this makes it possible to grow GaAsSb with the composition GaAs0.51Sb0.49, which, while normally within the miscibility gap at typical growth temperatures, can exist as a kinetically stable alloy.[1] This composition of GaAsSb is latticed matched to InP and is sometimes used in heterostructures grown on that substrate.
The bandgap and lattice constant of GaAsSb alloys are between those of pure GaAs (a = 0.565 nm, Eg = 1.42 eV) and GaSb (a = 0.610 nm, Eg = 0.73 eV).[3] Over all compositions, the band gap is 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 Eg = 0.67 eV, which is slightly below that of pure GaSb.[1]
A GaAsSb/GaAs-based heterostructure was used to make a near-infrared photodiode with peak responsivity centered at 1.3 μm.[7]
GaAsSb can be incorporated into III-V–based multi-junction solar cells to reduce the tunneling distance and increase the tunneling current between adjacent cells.[8]
References
^ abcdCherng, M. J., Stringfellow, G. G., Cohen, R. M. (1984). "Organometallic vapor phase epitaxial growth of GaAs0.5Sb0.5". Applied Physics Letters. 44 (7): 677–679. Bibcode:1984ApPhL..44..677C. doi:10.1063/1.94874.
^Madelung, O., Rössler, U., Schulz, M., eds. (2002). "GaAs(1-x)Sb(x), physical properties". Group IV Elements, IV-IV and III-V Compounds. Part b - Electronic, Transport, Optical and Other Properties. Landolt-Börnstein - Group III Condensed Matter. Vol. b. Springer-Verlag. pp. 1–13. doi:10.1007/10832182_25. ISBN978-3-540-42876-3.
^Vurgaftman, I., Meyer, J. R., Ram-Mohan, L. R. (2001). "Band parameters for III–V compound semiconductors and their alloys". Journal of Applied Physics. 89 (11): 5815–5875. Bibcode:2001JAP....89.5815V. doi:10.1063/1.1368156.
^Bolognesi, C. R., Dvorak, M. M. W., Yeo, P., Xu, X. G., Watkins, S. P. (2001). "InP/GaAsSb/InP double HBTs: a new alternative for InP-based DHBTs". IEEE Transactions on Electron Devices. 48 (11): 2631–2639. Bibcode:2001ITED...48.2631B. doi:10.1109/16.960389.
^Sun, X., Wang, S., Hsu, J. S., Sidhu, R., Zheng, X. G., Li, X., Campbell, J. C., Holmes, A. L. (2002). "GaAsSb: a novel material for near infrared photodetectors on GaAs substrates". IEEE Journal of Selected Topics in Quantum Electronics. 8 (4): 817–822. Bibcode:2002IJSTQ...8..817S. doi:10.1109/JSTQE.2002.800848. ISSN1558-4542.
