Optical properties of Cd{sub 0.9}Zn{sub 0.1}Te studied by variable angle spectroscopic ellipsometry between 0.75 and 6.24 eV

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Journal of Electronic Materials

DOI:https://doi.org/10.1007/s11664-999-0067-1· OSTI ID:362101

Yao, H W; Erickson, J C ^[1]; Barber, H B ^[2]; James, R B; Hermon, H ^[3]

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1. Univ. of Nebraska, Lincoln, NE (United States)
2. Univ. of Arizona, Tucson, AZ (United States)
3. Sandia National Labs., Livermore, CA (United States)

Cadmium zinc telluride (CZT) is a leading technological material for room-temperature gamma-ray and x-ray detectors. Optical properties of Cd{sub 0.9}Zn{sub 0.1}Te (CZT) were studied by variable angle spectroscopic ellipsometry (VASE). Measurements made by VASE were performed on CZT and CdTe samples in air at room temperature at multiple angles of incidence. A parametric function model was employed in the VASE analysis to determine the dielectric functions {epsilon} = {epsilon}{sub 1} + i{epsilon}{sub 2} in the range of 0.75 to 6.24 eV. A two-oscillator analytical model was used to describe the dielectric response of native oxides on CZT. Surface oxide optical properties and thickness on CZT were also determined in conjunction with the VASE measurement and analysis of a CdTe sample. Two samples of CZT of different oxide thicknesses were measured and their optical constants were coupled together in a multiple-sample, multiple-model VASE analysis to resolve correlations between fitting parameters. Effective medium approximation was used to describe the optical properties of the CZT oxide with roughness. A Kramers-Kronig self-consistency check of the real and imaginary parts of the Cd{sub 0.9}Zn{sub 0.1}Te dielectric functions was performed over the energy range 0.75 to 6.24 eV. A five-Lorentz-oscillator model was employed to describe the dielectric response of CZT in the range of 1.6 to 6.24 eV. Intensity transmission measurements were made on the Cd{sub 0.9}Zn{sub 0.1}Te and CdTe, showing the absorption energy band edges of {approximately}1.58 and 1.46 eV, respectively.

• Sponsoring Organization: USDOE
• OSTI ID: 362101
• Report Number(s): CONF-9810154--
• Journal Information: Journal of Electronic Materials, Journal Name: Journal of Electronic Materials Journal Issue: 6 Vol. 28; ISSN JECMA5; ISSN 0361-5235
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
CADMIUM TELLURIDES
DIELECTRIC PROPERTIES
ELLIPSOMETRY
GAMMA SPECTROMETERS
OPTICAL PROPERTIES
SEMICONDUCTOR DETECTORS
SPECTROSCOPY
X-RAY SPECTROMETERS
ZINC TELLURIDES