Reasons of high efficiency visual EL in monocrystal silicon

P.Jaguiro, S.Lazarouk, A. Ferrari

The planar, micro cylindrical and micro spherical reverse biased Shottky junctions are carefully considered to compare them and to find the differences, which can influence on the visible light emission efficiency. The detailed analyzing the avalanche conditions, field distributions, effective temperatures of hot electrons and light emission probabilities allows to derived the equations for spectra and power efficiency for each topology. It is appeared that in micro spherical junctions avalanche conditions is more difficult, so near the electrode exist significantly more strong electric field and temperature of the hot electrons is higher, than in planar junction. Significant increasing of the electron's temperature correspondingly improves the probability of visible photon emission. Calculated spectra shows blue shift and significant improving (some orders in magnitude) the power efficiency. Thus, analyzing the same process of light emission by avalanche, but at different topologies, shows the way to radical improve light emission silicon devices. Just achieved brightness and power efficiency are comparability with the best samples of porous silicon light emission diodes.