Optimisation of Er centers in Si for reverse biased light emitting diodes

Depending on the doping and annealing conditions, as well as the oxygen con tent, erbium produces a big variety of different centres in silicon. These centres can be distinguished by their fine structure patterns seen both in luminescence and in excitation spectroscopy. Centres with a well-defined ge ometry of their constituents exhibit very sharp line spectra. Such centres can be excited via recombination of electron-hole pairs. produced in a forw ard biased diode, with surprisingly high quantum efficiency below 100 K - b ut they are strongly quenched at higher temperatures. Another type of spect rum - with a much higher line width ( similar to 20 nm) and weak thermal qu enching up to 370 K is obtained after annealing at temperatures above 950 d egreesC. This type of spectrum is identified as being due to Er in SiO2-del ta precipitates. Such centres have much smaller quantum efficiencies for fo rward bias excitation than for reverse bins. We discuss properties that are important for the realisation of LED structures based on this type of cent res for room temperature (RT) operation. (C) 2001 Elsevier Science B.V. All rights reserved.