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CdTe thin films properties fabricated by hot wall epitaxy

Yevgen O. Bilevych ,  Andriy I. Boka ,  Joanna V. Gumenjuk-Sichevska ,  Fedor F. Sizov 

Institute of Semiconductor Physics NAS Ukraine, Kyiv, Ukraine

Abstract

CdTe thin films are widely used in semiconductor technology for many purposes: near-infrared detectors, optoelectronic devices and others. That is why great attention is paid to improve the existing methods of CdTe thin films fabricating to obtain films with repeatable thickness, morphology as well as electrical and optical properties.
CdTe thin films where prepared by hot wall epitaxy (HWE). The main feature of this method is the growth conditions that are rather close to the thermodynamic equilibrium. Such conditions are provided by quasi-close growing area and by the appropriate choice of the three temperature parameters: Tsource, Twall, Tsubstrate.
The thin films were grown on different substrates, such as BaF2, Si, SiO2, (110)CdTe. To investigate the fabricated films properties as a passivating material for IR technology they were also grown on narrow-gap Hg1-xCdxTe. The influence of the substrate materials on properties of epitaxial films were investigated. The best results were obtained for the following temperature parameters: Tsource = 653 K; Twall = 673 K; Tsubstrate = 393 K. The growth rate was estimated to be of the order of ~ 0,02 - 0,03 mkm min-1.
The Schottki barriers were prepared by thermal and chemical deposition of Au contacts on the grown CdTe layers. The current-voltage and capacitance-voltage investigations were performed to analyze their electrical properties. The samples exhibited the characteristics typical for the Schootky diodes.
Optical and photoelectrical properties were investigated by measurements of optical transmission spectra as well as the photoresponse and photoconductivity. For thin CdTe films transmission spectra are found to be similar to those ones obtained for thick films and bulk crystals. In the IR spectral region 2-15 mkm the optical transmission was ~ 60 %. As a test of the film quality, elastic strains were calculated from the shift of the absorption edge in the the transmission spectra

 

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Related papers

Presentation: poster at E-MRS Fall Meeting 2003, Symposium C, by Yevgen O. Bilevych
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-10 12:51
Revised:   2009-06-08 12:55