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Stark Effect for Donors in Double Quantum Wells

S. Rolnik, J. Adamowski

1995
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Acta Physica Polonica. A
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The problem of a hydrogenic donor in a semiconductor double quantum well under a hkogeneous electric field is studied by variational means. The energy levels corresponding to the quantum states 1s, 2s, 2p have been calculated with the help of the many-element variational basis consisting of the exponential functions. The influence of the electric field oii the donor binding energy is determined for different impurity positions. The 1s-2p transition energies have been calculated for a possible
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... ed for a possible comparison with experiment. PACS numbers: 73.20.Dx, 73.20.Hb Among semiconductor heterostructures, the double quantum wells (DQW) have attracted much interest in the past few years, since they can serve as a starting point for studying the semiconductor superlattices. As it has been recently observed [1] , an application of the electric field to the quantum well (QW) stuctures leads to the field-induced localization of electron states, which is manifested as the Stark ladder of electron energy levels. Doping such structures with impurities results in a considerable change in the electron charge distribution depending in which of the wells (with respect to the sign of the applied voltage) the attractive center is located. The influence of the electric field on the hydrogen-like donor quantum states for a single QW has been experimentally and theoretically studied by Yoo et al. [2] and Latge et al. [3] . The influence of the magnetic field on the donor states in the DQW stuctures has been investigated by Ranganathan et al. [4]. In the present paper, the properties of the donor states (1s, 2s, 2p) for the DQW under the static external electric field are determined by variational means. To the best of our knowledge, this effect has not been investigated by theoretical methods until now. We consider a hydrogenic model of the donor impurity in the DQW. The system consists of the electron and the positive donor center located in one of the wells. The DQW semiconductor structure is described by the potential energy profile which consists of the two wells of the same depth and thickness (denoted by VB and L, respectively) separated by the barrier of width W. We assume that the homogeneous electric field of the strength F is applied to the DQW stucture along the growth axis (z axis). The donor ionization by the field is neglected. Choosing (893)

doi:10.12693/aphyspola.88.893
fatcat:zr3kt7ivu5hx3idv5uzetjhqju