Semiconducting glass design for device applications

A method is presented by which stable amorphous semiconductors can be chosen for switching device applications. This method is based on the empirical relationship observed between the glass transition temperature, the band gap and the mean coordination number of covalent amorphous semiconductors. In particular, it is shown that tetrahedrally coordinated glasses with band gaps in the range 0.6–1.2 eV are excellent candidates for high reliability materials. One such material, a-CdAs₂, was studied in some detail and was found to be very stable and very easy to fabricate in thin film form. Both negative resistance and threshold switching devices were successfully fabricated with this material, and preliminary results from accelerated life testing are promising.