Optically writing erasable conductive patterns at a bandgap- engineered heterojunction

摘要

A heterojunction is formed between a pair of layers of different semiconductive materials whose work function difference produces a large band offset at the heterojunction. Donor or acceptor atoms are included in one regions that when photoexcited produce free charge carriers but leave behind charged centers that keep the photoexcited carriers localized. The large barrier at the heterojunction limits recombination of the free charge carriers and the charged centers and persistent photoconductivity results. This effect is used to form light operated switches. An illustrative example uses a layer of high purity gallium arsenide forming a heterojunction with a gallium-doped layer of zinc selenide.