Regular paper

UV distributed Bragg reflectors build from porous silicon multilayers

¹ CIDS-ICUAP. Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, México
² Laboratorio de Investigación y Desarrollo de Materiales Avanzados (LIDMA), Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón esquina Paseo Tollocan, Toluca Estado de México, 50110, México

^* lorr810813@gmail.com

Received: 12 November 2014
Revised: 1 March 2015

Abstract

UV Distributed Bragg reflectors were fabricated by a two-step thermal oxidation process over porous silicon multilayers (PS-ML), which were prepared by room-temperature electrochemical anodization of silicon wafers. The optical behavior of the PS-ML before and after oxidation was studied by reflectance measurements. It was observed an UV shift from 430 to 300 nm in the peak of the reflectance spectrum after oxidation of the PS-ML. This was attributed to the presence of silicon oxide over the surface of the silicon filaments. Such oxide also reduced the refractive index of each porous silicon monolayer. The bandgap of the PS-ML was calculated by the Kubelka-Munk approximation, which showed an increase in the bandgap from 3.11 to 4.36 eV after the thermal oxidation process. It was suggested that the observed optical response could opens the possibility of fabrication of UV optoelectronic devices based entirely in the silicon technology.