On the Quantum Confined Stark Effect in Some Semiconductor Nanostructures

In this work we will introduce quantum dots, wires and wells as nanostructure objects with different dimensionality. We will demonstrate the effect of applied external static electric field on the example of semiconductor quantum wells and the appearance of Stark effect. We will briefly allude to some of the optoelectronic devices using Stark effect. The influence of quantum well concentration profile and width on Stark shifts will be examined in case of the system GaAs-AlGaAs. The applicability of the model investigations for preliminary evaluation e.g. of the optimal Al concentration profile in order to improve the Stark effect characteristics in quantum wells is considered. The present work is motivated by the tremendous interest in the semiconductor nanostructures [1-4]. This interest is due to their actual and potential applications in various electro-optical devices. Modern electronic and optoelectronic devices are approaching nanometric dimensions and employ semiconductor nanostructures. Nanostructures can be of three (dots), two (wire) and one (well) dimension. Here, we define the nanostructure dimensionality as the number of dimensions where the translational symmetry is broken. Devices based on one-dimensional (1D) nanostructures (superlattices and quantum wells) have already entered the marketplace. As example, electronic devices based on quantum wells (QWs), such as the high electron mobility transistor, have shown outstanding performances. Long-wavelength lasers for modern telecommunications have active regions with a sequence of QWs obtained from the heterojunction of two or more semiconductors. Physical phenomena related to semiconductor nanostructures, such as confinement of carriers in zero, one or two dimensions, are of great interest and have contributed to the definition of new concepts in modern solid-state physics. Semiconductor heterostructures and particularly, double heterostructures, including QWs, wires, and dots, are today the subject of research of two-thirds of the semiconductor physics community [1]. The purpose of this paper is to describe the quantum confined Stark effect in some semiconductor nanostructures, namely in the semiconductor QWs. QWs are very thin layered semiconductor structures [1,2,5]. Most of their special properties are due to the quantum confinement of charge carriers (electrons and holes) in thin layers of one semiconductor “well” material sandwiched between other semiconductor ”barrier” layers. Quantum confinement of charge carriers forms the discrete energy levels in a QW for which the electronic and optical properties are quite different from the bulk semiconductors. Such good quality nanostructures