Photo and Electroluminescence of a-Si:Er:H
- PDF / 746,679 Bytes
- 12 Pages / 414.72 x 648 pts Page_size
- 96 Downloads / 223 Views
Trivalent erbium (Er3+) presents a characteristic intra 4f optical transition 41 3/2 -- I 5/2 at 1.54 jim when incorporated in several solid hosts. Hydrogenated amorphous silicon (a-Si:H) is a good candidate as a host for applications in optical communications and photonic integration. We have studied Er3+ photo and electroluminescence in a-Si:H prepared by co-sputtering from a silicon target partially covered with metallic erbium chunks. Since the presence of oxygen impurities enhances the luminescence intensity, we studied the influence of oxygen added to the sputtering gas on the material properties. We found that oxygen reduces the erbium incorporation into the films. We obtained samples presenting 1.54 [tm photoluminescence as deposited for a wide range of erbium concentrations. Maximum room-temperature photoluminescence efficiency is obtained for samples that contain - 1% [O]/[Si] concentrations. The temperature quenching is small, mainly due to the temperature dependence of the luminescence lifetime. Room temperature electroluminescence at 1.54 jim was observed in reverse biased Si/a-Si:Er:O:H/Al structures. INTRODUCTION Hydrogenated amorphous silicon (a-Si:H) has been extensively studied over more than 20 years. As a result, several applications beyond the original photovoltaic devices have blossomed. Nowadays a-Si:H is widely used in electronic applications such as thin film transistors for flat panel displays and image detectors are expected to be in the market soon. A new field of applications, namely photonic communications, is starting to become a real possibility after efficient room temperature rare-earth extrinsic luminescence has been obtained in this material. Erbium is easily introduced in the a-Si:H network an presents efficient room temperature luminescence at 1.54 pjm. Photonic technology is rapidly achieving more and more importance in telecommunications, replacing conventional electronic media. Nowadays, the amount of information flowing constantly around the world requires unprecedented throughputs in the telecommunication systems. The use of silica-based optical fibers has allowed a bandwidth increase of orders of magnitude relative to microwaves or cable communications. Presently the state of the art corresponds to a total bit rate exceeding 2.6 Tb/s. (2.6x1012 b/s) over 120 km [1]. Conventional silica optical fibers present minimum attenuation losses at wavelengths near 1.5 ýim, defining the so-called "third spectral window" (the others are at 0.9 and 1.3 jim). One important challenge to materials scientists presently consists on developing reliable and cheap light emitters at this wavelength. The most widely used light source consists of near-band-edge lasers made from III-V alloys, which suffer from the relatively high temperature coefficients of their energy gaps and thus require precise temperature control in order to present acceptable performances. Moreover, their high cost makes large scale consumer applications prohibitive. From a technological point of view, a light source with
Data Loading...
