PHOTOINDUCED METASTABLE LATTICE DILATION OF CDF2-IN CRYSTALS

A novel technique for measuring differential lattice dilation by scann ing tunneling microscope is proposed. The method was used to measure t he metastable lattice dilation caused by a deep-shallow phototransform ation of bistable In impurities in CdF2 crystals. A total linear cryst al shrinkage of 1.8 x 10(-6) results from a partial counterbalancing o f the lattice contraction associated with the photoionized deep locali zed In state by a lattice expansion caused by weakly bound electrons a t the shallower hydrogenlike state of the bistable In donors. (C) 1997 American Institute of Physics.