Transmission for a finite superlattice with a linear modulation of the potential barriers height.
- PDF / 315,338 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 91 Downloads / 139 Views
Transmission for a finite superlattice with a linear modulation of the potential barriers height. K. A. Rodríguez-Magdaleno, J. C. Martínez-Orozco and D. A. Contreras-Solorio. Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060. Zacatecas, Zac. México. ABSTRACT Using the transfer matrix method and the Ben Daniel-Duke equation for variable mass electrons propagation, we calculate the transmittance for a finite superlattice where the potential barriers height follows a linear dependence like that of an inverted “V” letter. The energy dependence of the transmittance presents intervals of stopbands and nearly flat passbands. We calculate these properties for several numbers of barriers as well as for different barrier and wells widths and compare those with a regular superlattice. Keywords: III-V, Layered, Devices. INTRODUCTION The subject of propagation of any kind of waves in layered structures is very important. One of their important applications is as reflector structures and as filters. The search for energy, electronic, optical and acoustic filters is an interesting and active field. There have been proposals of energy passband filters using quantum superlattices with a Gaussian potential profile [1, 2]. These layered structures allow the incident electrons to be nearly totally transmitted when the impinging electron energy is in the passband energy region. Also, a complete reflection occurs when the impinging energy is in the stopband energy region. The idea behind using these types of structures is that a Gaussian profile provides a slowly varying potential for the layers, which can improve the transmission of electrons through the multilayer system. Following the idea of the superlattices with a Gaussian potential profile, layered omnidirectional optical mirrors have been proposed where the refractive index varies according to the envelope of a Gaussian function, using only normal materials [3] and using also metamaterials [4]. These systems were proposed only as omnidirectional mirrors but their properties as optical filters were not investigated. However, there is a proposal of a multilayer optical filter where the refractive index of the layers is modulated by a Gaussian function [5]. Likewise, there is a proposal of a layered acoustic filter where the characteristic acoustic impedance of the layers is modulated by a Gaussian distribution [6]. In this work we propose a structure where the height of the potential barriers follows a linear profile like that of an inverted “V” letter. The spectrum of eigenenergies for this type of structure consists of quasibands or passbands separated by energy gaps or stopbands. For the calculations we use the transfer matrix method and the Ben Daniel-Duke equation for variable mass electrons [7]. The spectrum of transmittance of the structure presents stopbands and nearly flat transmission bands of energy. In the next section we introduce the theoretical background, then we present some of our results
Data Loading...
