Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double delta-doped quantum wel
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Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double delta-doped quantum well in GaAs with a Schottky barrier potential. J. G. Rojas-Briseño1, J. C. Martínez-Orozco1, I. Rodríguez-Vargas1, C. A Duque2 and M. E. Mora-Ramos2,3. 1 Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060. Zacatecas, Zac. México. 2 Instituto de Física, Universidad de Antioquia, AA 1226, Medellín, Colombia. 3 Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, C.P. 62209, Cuernavaca, Morelos, México. ABSTRACT Semiconductor devices have been improved by using delta-doped quantum well (DDQW) of impurities due to the great amount of charge carriers it provides. The first proposals consisted of a DDQW close to the Schottky barrier potential in the gate terminal in a FET [1]. In this work we reported the energy levels spectrum for n-type double-DDQW with a Schottky barrier (SB) at their neighborhood in a Gallium Arsenide (GaAs) matrix. In addition to consider only the linear optical approximation we take into account the third order correction to the absorption coefficient and the refractive index change. We report those properties as a function of the Schottky Barrier Height (SBH), several separation distances between the DDQWs, and hydrostatic pressure effects. The results shown that the magnitude of intensity resonance peaks are controlled by the asymmetry of the DDQW+SB. Keywords: electronic structure, optical properties, III-V. INTRODUCTION Spatial localization of impurities in a single monolayer of a semiconductor crystal represents the ultimate physical limit of dopant distributions. Delta-doping is one of several terms used to name it [1-5]. Schubert and Ploog [6] proposed the δ-FET, a system where the conduction channel between the drain and the source is formed by a δ-doped layer. It is a system consisting of a metal-semiconductor and a DDQW, with the quasi-two-dimensional electronic cloud of the well being affected by the electric field of intensity Vc /d, where Vc is the height of the Schottky barrier and d is the distance separating the δ-well from the barrier. Self-consistent as well as analytical modeling of delta-doped field effect transistors were put forward by Gaggero-Sager et al. [7,8]. In the latter work, the analytical description of the confining potential profile was given along the lines of the Thomas-Fermi approximation introduced by Ioriatti [9]. The nonlinear optical properties in this kind of structures had not been investigated until very recently. Martínez-Orozco et al. studied the optical absorption and the relative change in the refractive index in a n-type δ-doped GaAs FET [10]. The aim of the present work is to extend such an investigation to the case of a GaAs n-type δ-FET-like configuration, with an asymmetric double delta well configuration, looking for a possible amplification of the nonlinear optical response in these systems, and taking into account the eff
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