High Efficiency Light Emission Devices in Silicon
- PDF / 471,019 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 58 Downloads / 249 Views
I2.1.1
High Efficiency Light Emission Devices in Silicon Maria E. Castagna 1 , Salvatore Coffa 1 , Mariantonietta Monaco1 , Anna Muscara’1 , Liliana Caristia1 , Simona Lorenti1 , Alberto Messina1 1 STMicroelectronics, Corporate Technology R&D, Stradale Primosole 50, 95121, Catania, Italy. ABSTRACT We report on the fabrication and performances of the most efficient Si- based light sources. The devices consist of MOS structures with erbium (Er) implanted in the thin gate oxide. The devices exhibit strong 1.54 µm electroluminescence at 300K with a 10% external quantum efficiency, comparable to that of standard light emitting diodes using III-V semiconductors. Emission at different wavelenghts has been achieved incorporating different rare earths (Ce, Tb, Yb, Pr) in the gate dielectric. The external quantum efficiency depends on the rare earth ions incorporated and ranges from 10% (for an Tb doped MOS) to 0.1% (for an Yb doped MOS). RE excitation is caused by hot electrons impact and oxide wearout limits the reliability of the devices. Much more stable light emitting MOS devices have been fabricated using Er-doped SRO (Silicon Rich Oxide) films as gate dielectric. These devices show a high stability, with an external quantum efficiency reduced to 0.2%. In these devices Er pumping occurs part by hot electrons and part by energy transfer from the Si nanostructures to the rare earth ions, depending by Si excess in the film. Si/SiO 2 Fabry-Perot microcavities have been fabricated to enhance the external quantum emission along the cavity axis and the spectral purity of emission from the films that are used as active media to realize a Si based RCLED (resonant cavity light emitting diode). These structures are realized by chemical vapour deposition on a silicon substrate. The microcavities are tuned at different wavelengths: 540nm, 980nm and 1540nm (characteristic emission wavelengths respectively for Tb, Yb and Er). The reflectivity of the microcavities is of 97% and the quality factor ranges from 60 (for the cavity tuned at 980nm) to 95 (for the cavities tuned at 540nm and 1540nm). INTRODUCTION Si is the semiconductor of choice for the fabrication of advanced electronic devices. Hence implementation of efficient optical function in Si would allow us to use the mature and low cost Si Ultra Large-Scale Integration (ULSI) technology for the fabrication of integrated optoelectronic circuits [1], [2]. Si physical properties make it unsuitable for efficient light emission and modulation at room temperature. The implementation of efficient optical functions in Si would greatly simplify the integration of electronic and photonic devices. The first goal is to fabricate efficient and electrically-driven room temperature ligth emission sources in Si. For the application in telecomunication field emission at 1.54 µm is requested. In this paper we propose a Si based light source consisting of a MOS structure with Er implanted in the thin gate oxide. This device shows a 10% external quantum efficiency at room temperature, comparable to
Data Loading...
