B.J. Cantwell

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.

Modelling of the growth of ternary compound cadmium zinc telluride (in a semi-open Markov-like system) from the binary sources CdTe and ZnTe

A model to describe the growth of Cd 1-x Zn x Te (CZT) in the multi-tube physical vapour transport (MTPVT) system is presented. This is a novel multi-tube vapour growth system developed at the University of Durham, based on separate vertical source and growth tubes connected by a horizontal optically heated crossmember which incorporates a capillary to regulate the mass flow. Growth takes place on a seed crystal in a semi-open Markov-like arrangement. During crystal growth, the mass transport is directly monitored by in situ measurements of the vapour pressures on the either side of the capillary using optical absorption. This model provides an estimate of the mass transport rate of the source materials CdTe and ZnTe.

The growth of CdTe bulk crystals using the multi-tube physical vapour transport system.

The control of vapour transport is central to the growth of any crystal from the gas phase and, therefore, a novel multi-tube physical vapour transport (MTPVT) system has been developed at the University of Durham which addresses this requirement directly. This paper reports recent work including some preliminary modelling of the transport in the MTPVT system. A capillary tube is used in the MTPVT system as a flow restrictor and the mass transport rate with respect to pressure drop across the capillary calibrated. The mass of CdTe transported from the source charge to growing crystal through the crossmember capillary is investigated over two separate growth runs of the MTPVT system and the results compared with the values predicted by modelling. The CdTe crystals grown using the MTPVT system have been quality tested using defect revealing etching, photoluminescence measurements, and X-ray diffraction analysis.

Growth of cadmium telluride crystals for sensor use

Despite its intrinsic advantages as a sensor material for the detection of gamma and X radiation, CdTe has proven 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

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.

Novel method for the growth of high quality cadmium telluride crystals for use in X-ray and gamma-ray sensors

Although widely used as a sensor material for the detection of /spl gamma/ and X radiation, CdTe has proved a difficult material to produce. We report on a vapour phase technique that provides potentially significant advantages over current melt growth technologies. Crystals of 50 mm in diameter with low strain and etch pit densities have been produced.