Optoelectronic Device Applications Of Doping Superlattices

Abstract

Optoelectronic Device Applications of Doping SuperlatticesGottfried H. DohlerInstitut fur Technische Physik, Universitat Erlangen-Nurnberg, Erwin-Rommel-Str. 1, 8520 Erlangen, FRGAbstractDoping Superlattices, composed of alternating n- and p-dopedwith intrinsic regions in between (n-i-p-i structures, optical properties. Their potential for a wide variety of optical devices is discussed and recent results are reported.semiconductor layers, possibly exhibit novel electrical and new electro-optical and opto-1. IntroductionBasically there are two kinds of semiconductor Superlattices. 1 The compositional super- lattices consist of a periodic sequence of ultrathin layers of two different semiconductor materials. The doping Superlattices are made of a uniform semiconductor material which is periodically modulated only by alternating n and p doping, possibly with intrinsic (i) layers in between ' . Because of this periodic sequence of doping, these structures are also called n-i-p-i - crystals (this name is frequently used also for structures which do not contain the intrinsic layers). In both cases a periodic superlattice potential arises and leads to strong changes of the electronic structure and, consequently, of the electronic and optical properties of the material. In the case of the compositional superlattice, the periodic potential is due to the different bandgap of the two components of the superlattice. The conduction and the valence band discontinuity add up to the difference inDIRECTION OF PERIODICTY, z