International Standard Electric Corporation

Edward John Thrush

Gillies D Pitt

Peter D Greene

David H Whysall

A Hall effect device comprises a thin substrate free epitaxially grown semiconductor body mounted in a magnetically permeable, e.g. ferrite, housing. The layer, which is preferably gallium arsenide or gallium indium arsenide, is grown on a substrate which, after device processing is complete, is removed by a selective etching process. In view of the relatively high sensitivity and good noise characteristics such a device with its flux concentrator is small, since the flux concentrators are themselves much smaller than with conventional Hall effect systems. Other semiconductor materials from which the novel thin Hall effect devices can be made include silicon.

Method of making a Hall effect device

This invention comprises methods and apparatus for bonding a transmission type III-V photocathode to a transparent substrate. An R.F. susceptor arrangement produces a marked temperature gradient for allowing the surface of the glass to conform to the shape of the semiconductor material without softening the bulk of the glass. The bonded assembly is then carefully annealed in an annealing furnace.

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Stansted Mountfitchet, United Kingdom

Edward John Thrush