Arnab Basu

Thick epitaxial CdTe films grown by close space sublimation on Ge substrates

This paper reports, for the first time, the successful growth of 200 µm thick CdTe films on mis-oriented Ge(1 0 0) substrates by a cost-effective optimized close space sublimation method. It is found that, as the thickness increases to a few hundred micrometres, subgrains are formed probably as a result of the large density of dislocations and strain within the initial interfacial layers. The films are of high quality (x-ray rocking curve width ~100 arcsec) and high resistance (~109 Ω cm), and are thus candidates for x-ray and γ-ray detectors.

Electroless Contact Study on CdTe Nuclear Detectors: New Results and Element Deposition

Electroless deposited contacts are frequently used for II–VI semiconductor materials and particularly on CdTe/CdZnTe. This chemical deposition method creates a stronger chemical bond and few nested interfacial layers between the contact and the semiconductor when compared to physical deposition methods such as sputtering or evaporation. This method also forms a moderate quasi-ohmic contact which eliminates the spectral degradation problem caused by the polarization effect.

New approach to deposition of W and Mo on CdTe by the electroless method

The feasibility of depositing tungsten and molybdenum contacts on cadmium telluride by the electroless method has been demonstrated.

Heteroepitaxial growth and properties of crystals of CdTe on GaAs substrates

This paper reports on the use of a seeded vapour phase technique to grow bulk crystals of CdTe onto commercially available 50 mm diameter (211)B GaAs substrates. High quality crystals, several mm in thickness were grown on the GaAs at linear growth rates of ~ 120 μm/h. Characterisation by double and triple axis XRD showed the best crystals to have θ-2θ FWHMθ values of ~ 24 arc sec corresponding to low strain dispersion (< 2×10-4). Rocking curve scans included two to three sharp peaks, indicative of some small mosaicity. When mapped across a the surface of the crystal, the FWHM was uniform and < 93 arc sec. Contactless resistivity showed a similar degree of uniformity with a mean value of 4.4 × 109 ± 1.6 × 109 Ω cm. Infrared microscopy showed that within the resolution of the microscope (~ 5 μm) there were very few Te inclusions.

Growth of thick CdTe:Cl Layers of large diameter on ZnTe buffered ge seeds for room temperature radiation detection

ZnTe buffer layers have been found to greatly improve the quality of CdTe layers grown on germanium seeds.

Vapour phase growth of 100 mm diameter cadmium telluride boules on GaAs seeds

The Multi-Tube physical Vapour Transport (MTPVT) crystal growth technique has been scaled to grow single crystals of cadmium telluride 100 mm in diameter.

Study and characterization of guarded small pixel contact geometries on CdTe

Optimizing the guard potential of a guarded small pixel detector has been shown to enhance detector resolution.

Growth of high crystalline quality CdTe layers on 100 mm diameter Ge substrates for room temperature radiation detection

Uniform layers of cadmium telluride have been successfully grown hetero-epitaxially on germanium seeds up to 100 mm in diameter. X-ray diffraction studies show high structural quality for layers up to 1.4 mm thick. By doping with chlorine, resistivities up to 1 × 109 Ωcm have been achieved.

In-situ monitoring during vapour phase growth of bulk crystals of cadmium zinc telluride

In-situ laser reflectance measurements and photography have been made during the hetero-epitaxial nucleation and growth of cadmium zinc telluride on GaAs seeds. Fabry-Pèrot oscillations are observed in the reflectance signal which persist up to several tens of micrometres layer thickness and the average reflected intensity provides information on the surface morphology of the growing crystal.

Growth of high quality bulk cadmium telluride crystals for use in X-ray and gamma-ray sensors

Despite its intrinsic advantages as a sensor material for the detection of gamma and X radiation, CdTe has proved a difficult material to produce consistently and in sufficient quantities. We report further developments of a vapour phase technique, which has provided significant advantages over current melt growth technologies. Crystals of up to 50 mm in diameter have been produced with increased growth rates up to 12 mm/day.