Band offsets for mismatched interfaces: The special case of ZnO on CdTe (001)

Journal Article · Fri Nov 15 00:00:00 EST 2013 · Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films

DOI:https://doi.org/10.1116/1.4816951· OSTI ID:22224100

Jaffe, John E.; Kaspar, Tiffany C.; Droubay, Timothy C. ^[1]; Varga, Tamas ^[2]

---

1. Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)
2. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)

High-quality planar interfaces between ZnO and CdTe would be useful in optoelectronic applications. Although CdTe is zinc blende with cubic lattice constant a = 6.482 Å while ZnO is hexagonal wurtzite with a = 3.253 Å and c = 5.213 Å, (001)-oriented cubic zinc blende ZnO films could be stabilized epitaxially on a CdTe (001) surface in an √2 × √2 R45° configuration with a lattice mismatch of <0.5%. Modeling such a configuration allows density-functional total-energy electronic-structure calculations to be performed on several interface arrangements (varying terminations and in-plane fractional translations) to identify the most likely form of the interface, and to predict valence-band offsets between CdTe and ZnO in each case. Growth of ZnO on Te-terminated CdTe(001) is predicted to produce small or even negative (CdTe below ZnO) valence band offsets, resulting in a Type I band alignment. Growth on Cd-terminated CdTe is predicted to produce large positive offsets for a Type II alignment as needed, for example, in solar cells. To corroborate some of these predictions, thin layers of ZnO were deposited on CdTe(001) by pulsed laser deposition, and the band alignments of the resulting heterojunctions were determined from x-ray photoelectron spectroscopy measurements. Although zinc blende ZnO could not be confirmed, the measured valence band offset (2.0–2.2 eV) matched well with the predicted value.

• OSTI ID: 22224100
• Journal Information: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 31, Issue 6; Other Information: (c) 2013 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALIGNMENT
CADMIUM TELLURIDES
CRYSTAL DEFECTS
CUBIC LATTICES
DENSITY FUNCTIONAL METHOD
ELECTRONIC STRUCTURE
ENERGY BEAM DEPOSITION
EPITAXY
EV RANGE
HETEROJUNCTIONS
INTERFACES
LASER RADIATION
PULSED IRRADIATION
SEMICONDUCTOR MATERIALS
SOLAR CELLS
THIN FILMS
X-RAY PHOTOELECTRON SPECTROSCOPY
ZINC OXIDES
ZINC SULFIDES