Development and characterisation of electroluminescent diodes based on porous Si Integration with the control electronics in CMOS technology

The demonstration of efficient and reliable light emitting diodes (LED) in a silicon based system will have a great impact on photonics. A first step to this goal is the demonstration of an efficient Si based LED for which porous silicon (PS) is a good candidate. State of the art PS based LED devices have external quantum efficiency of more than 1% even if the power efficiency is still in the order of 0.1% due to the very high turn-on voltage of these diodes, while integration of PS based LED with microelectronic circuit has been also demonstrated. In this project we propose a new device structure based on an heterojunction between crystalline Si and PS. The idea is based on the realisation that efficient hole injection exists. With our device structure we want to mimic this interface also for electron injection. This is obtained through an electrochemical anodization of a p-type silicon wafer where n+-type doped stripes are formed by implantation. Due to the etching selectivity of the PS formation process when performed in the dark, the n+-type doped stripes are not etched and, instead, are floating over the PS layer. The resulting structure is composed of an array of n+-type doped crystalline Si/PS junction. The fabrication of the test structure is within the CMOS fab-line of ITC-irst and it comprehends all standard processing but for the fabrication of the PS layer, which is an electrochemical attak, performed within the Department of Physics of Trento