Semiconductor device and method of manufacture thereof

Abstract

A structure including a substrate, an intermediate layer provided and formed directly onto the substrate, a transition region, and a group II-VI bulk crystal material provided and formed as an extension of the transition region. The transition region acts to change the structure from the underlying substrate to that of the bulk crystal. In a method of manufacture, a similar technique can be used for growing the transition region and the bulk crystal layer.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a semiconductor device and a method of manufacture therefore. In particular, the present invention relates to a device comprising a group II-VI material formed on a substrate of a dissimilar material, and a method for forming such a structure.DISCUSSION OF THE PRIOR ART[0002]Single crystal materials have a number of important applications. For example, bulk cadmium telluride (CdTe) and cadmium zinc telluride (CZT) semiconductors are useful as x-ray and gamma-ray detectors which have application in security screening, medical imaging and space exploration amongst other things.[0003]For many applications, it is desired to have single crystals of large size and thickness, which can be formed rapidly with optimum uniformity and minimum impurities.[0004]Traditionally, single crystals have been formed using direct solidification techniques, such as by the Bridgman, travelling heater (THM), gradient freeze (GF) or other liquid ph...

AI Technical Summary

Benefits of technology

[0023]Although one advantage of the present invention is the ability to produce large size crystal materials for use in large detectors or the like, it is possible to divide the substrate and crystal material grown on the substrate into smaller pieces. By producing a single, large piece of crystal and then dividing this up into smaller pieces, it is considered possible to produce the required crystal material more quickly and with greater consistency than would be the case if the smaller pieces required were formed individually.

Problems solved by technology

It has previously been considered that crystal mismatches between a substrate and bulk crystal material having different lattice structures prevent the formation of the bulk crystal material on such substrates, or would result in unacceptable stresses between the materials affecting the device unacceptably.

For example, it is not generally considered possible to provide a cadmium telluride crystal material, which will have a lattice parameter a=6.481 Å directly onto a silicon substrate which will have a lattice parameter a=5.4309 Å due to the lattice mismatch.

Accordingly, this limits the bulk crystal material that can be grown on any given substrate.

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