INTERBAND ABSORPTION OF LONG-WAVELENGTH RADIATION IN DELTA-DOPED SUPERLATTICES BASED ON SINGLE-CRYSTAL WIDE-GAP SEMICONDUCTORS

A new type of superlattice formed in a single-crystal nondegenerate, w ide-gap semiconductor by a sequence of pairs of closely spaced, delta- doped donor and acceptor layers is proposed. It is shown that because of the superstrong electric fields generated between these delta-doped layers, the electroabsorption of long-wavelength radiation is determi ned by tunneling optical transitions of electrons from the heavy-hole band (in contrast to the case of moderately strong fields when the ele ctroabsorption is determined by light holes). The magnitude of the ele ctroabsorption is close to the interband absorption for light and is v irtually independent of the photon energy up to the far-infrared regio n. It was found that in the proposed InSb-based superlattice the absor ption in superstrong fields can exceed 10(3) cm(-1) up to radiation wa velengths approximately equal to 50-100 mu m. It is noted that because of the spatial separation of the photogenerated electrons and holes, their lifetime and the long-wavelength sensitivity of such a superlatt ice have giant values. (C) 1998 American Institute of Physics.