Cu-Pt type ordering in III-V semiconductor
One of the most studied atomic ordering is CuPt type ordering in III-V semiconductor alloy in chemistry and physics. It occurs in III-V alloy when the cation planes take an alternate sequence of A-rich and B-rich plane following AxB1−xC. The resulting structure is usually called as superlattice-like structure along [1-11] or [-111] – called (111) B plane, or along [-1-1-1] or [11-1] – called (111) A plane. The two ordering direction is thus called CuPt type A and B ordering.
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The same type ordering is also observed in II-VI alloy such as CdZnTe alloy. The ordering sequence viewed on atomic planes along [-111] and [1-11] reveals Cd and Zn alternating planes.
This ordering reduces the lattice symmetry ordering to L11 and leads to change of its optical and electrical properties. The apparent effects are: band gap reduction, valence band splitting, and optical anisotropy. For instance, in CuPt type B ordering, the L point of the Brillouin zone fold back to the Γ-point, and the folded band “repels” the original conduction band minimum and bring down the bottom of conduction band.
AlInP epilayers grown by metal-organic vapour-phase epitaxy on GaAs substrates exhibit CuPt-B-type spontaneous atomic ordering.[2] Additionally, CuPt-type structures were observed in CdZnTe during metal-organic vapor phase epitaxy.[3]
References
- Lee, H. S.; Kwon, M. S.; Lee, J. Y.; Kim, T. W.; Park, H. L. (September 2003). "Formation of the CuPt-type ordered structure in CdxZn1−xTe epilayer grown on ZnTe buffer layer on (001) GaAs substrate". Journal of Materials Science Letters. 22 (18): 1263–1267. doi:10.1023/A:1025458102274. S2CID 137365490. Retrieved 2021-05-02.
- Jinghua, Zhao; Xiaohong, Tang; Jinghua, Teng (27 May 2009). "Atomic ordering of AlInP grown by MOVPE at different temperatures in pure ambient N2". CrystEngComm. 11 (6): 1068–1072. doi:10.1039/B817012F. ISSN 1466-8033. Retrieved 7 July 2021.
- Kwon, Myoung Seok; Lee, Jeong Yong; Suh, Sang Hee (1998). "Observation of CuPt-Type Ordered Structure in CdZnTe during Organometallic Vapor Phase Epitaxial Growth". Japanese Journal of Applied Physics. 37 (1A): L21. Bibcode:1998JaJAP..37L..21K. doi:10.1143/JJAP.37.L21. ISSN 1347-4065. S2CID 119446784. Retrieved 7 July 2021.