Impact of extended defects on recombination in CdTe heterostructures grown by molecular beam epitaxy

Journal Article · Mon Aug 29 00:00:00 EDT 2016 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4961989· OSTI ID:22590495

Zaunbrecher, Katherine N. ^[1]; Kuciauskas, Darius; Dippo, Pat; Barnes, Teresa M. ^[2]; Swartz, Craig H.; Edirisooriya, Madhavie; Ogedengbe, Olanrewaju S.; Sohal, Sandeep; Hancock, Bobby L.; LeBlanc, Elizabeth G.; Myers, Thomas H. ^[3]

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1. Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
2. National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
3. Materials Science, Engineering and Commercialization Program, Texas State University, San Marcos, Texas 78666 (United States)

Heterostructures with CdTe and CdTe{sub 1-x}Se{sub x} (x ∼ 0.01) absorbers between two wider-band-gap Cd{sub 1-x}Mg{sub x}Te barriers (x ∼ 0.25–0.3) were grown by molecular beam epitaxy to study carrier generation and recombination in bulk materials with passivated interfaces. Using a combination of confocal photoluminescence (PL), time-resolved PL, and low-temperature PL emission spectroscopy, two extended defect types were identified and the impact of these defects on charge-carrier recombination was analyzed. The dominant defects identified by confocal PL were dislocations in samples grown on (211)B CdTe substrates and crystallographic twinning-related defects in samples on (100)-oriented InSb substrates. Low-temperature PL shows that twin-related defects have a zero-phonon energy of 1.460 eV and a Huang-Rhys factor of 1.50, while dislocation-dominated samples have a 1.473-eV zero-phonon energy and a Huang-Rhys factor of 1.22. The charge carrier diffusion length near both types of defects is ∼6 μm, suggesting that recombination is limited by diffusion dynamics. For heterostructures with a low concentration of extended defects, the bulk lifetime was determined to be 2.2 μs with an interface recombination velocity of 160 cm/s and an estimated radiative lifetime of 91 μs.

• OSTI ID: 22590495
• Journal Information: Applied Physics Letters, Vol. 109, Issue 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CADMIUM TELLURIDES
CHARGE CARRIERS
CRYSTALLOGRAPHY
DIFFUSION LENGTH
DISLOCATIONS
EMISSION SPECTROSCOPY
INDIUM ANTIMONIDES
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
PHONONS
PHOTOLUMINESCENCE
RECOMBINATION
TIME RESOLUTION