Raman Scattering Study of Lattice Vibrations in the Type-II Superlattice
- Univ. of North Carolina, Charlotte, NC (United States). Optical Science and Engineering Graduate Program and Dept. of Electrical and Computer Engineering
- Arizona State Univ., Tempe, AZ (United States). Center for Photonics Innovation and School of Electrical, Computer and Energy Engineering
- Georgia Inst. of Technology, Atlanta, GA (United States). Center for Compound Semiconductors and School of Electrical and Computer Engineering
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
The InAs/InAs1-x Sbx superlattice system distinctly differs from two well-studied superlattice systems GaAs/AlAs and InAs/GaSb in terms of electronic band alignment, common elements at the interface, and phonon spectrum overlapping of the constituents. This fact leads to the unique electronic and vibrational properties of the InAs/InAs1-xSbx system when compared to the other two systems. Here in this work, we report a polarized Raman study of the vibrational properties of the InAs/InAs1-x Sbx superlattices (SLs) as well as selected InAs1-xSbx alloys, all grown on GaSb substrates by either MBE or metalorganic chemical vapor deposition (MOCVD) from both the growth surface and cleaved edge. In the SL, from the (001) backscattering geometry, an InAs-like longitudinal optical (LO) mode is observed as the primary feature, and its intensity is found to increase with increasing Sb composition. From the (110) cleaved-edge backscattering geometry, an InAs-like transverse optical (TO) mode is observed as the main feature in two cross-polarization configurations, but an additional InAs-like “forbidden” LO mode is observed in two parallel-polarization configurations. The InAs1-xSbx alloys lattice matched to the substrate ( xSb ~ 0.09) grown by MBE are also found to exhibit the forbidden LO mode, implying the existence of some unexpected [001] modulation. However, the strained samples (xSb~ 0.35) grown by MOCVD are found to behave like a disordered alloy. The primary conclusions are (1) the InAs-like LO or TO mode can be either a confined or quasiconfined mode in the InAs layers of the SL or extended mode of the whole structure depending on the Sb composition. (2) InAs/InAs1-xSbx and InAs/GaSb SLs exhibit significantly different behaviors in the cleaved-edge geometry but qualitatively similar in the (001) geometry. (3) The appearance of the forbidden LO-like mode is a universal signature for SLs and bulk systems resulting from the mixing of phonon modes due to structural modulation or symmetry reduction.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); US Army Research Office (ARO)
- Grant/Contract Number:
- AC04-94AL85000; W911NF-10-1-0524; NA0003525
- OSTI ID:
- 1467461
- Alternate ID(s):
- OSTI ID: 1394874
- Report Number(s):
- SAND-2017-10149J; PRAHB2; 657091
- Journal Information:
- Physical Review Applied, Vol. 8, Issue 3; ISSN 2331-7019
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Raman scattering study of InAs/GaInSb strained layer superlattices
A structural investigation of compositionally graded InAs/sub x/Sb/sub 1-x/ buffer layers