WRITING ERASABLE METALLIC PATTERNS IN INSULATING ALXGA1-XASDX

We have optically written persistent but erasable metallic features in insulating epilayers of AlxGa1-xAs doped with Si and Se, which form DX centers. The photocarriers, which remain in the AlxGa1-xAs layer, move freely in the conduction band but are confined to the exposed regions. We demonstrate this confinement by optical excitation in a striped pattern; the resulting modulation of the free carrier density is evinced by an anisotropy of the sample conductance parallel and perpendicular to the stripes. The anisotropy, like the photoconductivity itself, is persistent at low temperatures. Erasure is achieved by thermal annealing. We estimate that features can be written with better than 1000 angstrom resolution. (C) 1994 American Institute of Physics.