Temperature dependence and quenching processes of the intra-4fluminescence of Er in crystalline Si

Abstract

The luminescence quenching of Er in crystalline Si at temperatures between 77 and 300 K is investigated. Samples were prepared by solid-phase epitaxy of Er-implanted amorphous Si layers with or without 0 codoping. After epitaxial regrowth at 620'C, thermal annealing at 900'C for 30 sec was performed in order to eliminate residual defects in the regrown layer and electrically and optically activate the Er ions. Measurements of photoluminescence intensity and time decay were performed as a function of temperature and pump power. By increasing the temperature from 77 K to room temperature the luminescence intensity decreases by -three orders of magnitude in the Er-doped sample without 0 codoping, but only by a factor of 30 in the 0-doped sample. In this sample room-temperature photoluminescence and electroluminescence have been observed. Time-decay curves show a fast initial decay (-100psec) followed by a slow decay (-1 msec), with the relative intensity of these two components depending on temperature, pump power, and 0 codoping. The decay curves can be fitted by a sum of two exponential functions revealing the existence, in both samples, of two different classes of optically active Er sites. The concentration of excitable sites belonging to the slow-decaying class is similar for the samples with or without 0 codoping and rapidly decreases when temperature is increased. At temperatures above 150 K the Er luminescence is dominated by the fast-decaying centers the concentration of which is greatly increased by the presence of O. It is found that in the absence of oxygen roomtemperature luminescence is hampered by the limited amount of excitable Er ions. In contrast, in 0-doped samples the nonradiative decay of excited Er is the main quenching mechanism. The main factors determining the temperature quenching of Er luminescence and the crucial role of oxygen are discussed.

Electron paramagnetic resonance and photoluminescence study of Er-impurity complexes in Si

“…24 x is the crystal-field mixing term and is expressed in terms of the ratio of B 4 to B 6 and runs from Ϫ1 to ϩ1. The eigenvectors of the Hamiltonian are a combination of the fourth-and sixth-order crystal-field potentials.…”

“…Coimplantation with either O or F has been shown to help in suppressing precipitation and Er concentrations as high as of 1ϫ10 19 /cm 3 have been incorporated in a goodquality Si single crystal by ion implantation. 6,13 These beneficial effects have been attributed to modifications in the local environment of the Er atom through the formation of Er-impurity complexes. [14][15][16] It is therefore of great interest to determine the structure of these complexes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The 4f electrons are shielded from the full effects of the host crystal field and this results in the intra-4f shell optical transitions being both sharp and nearly independent of the host material. Furthermore, due to the close proximity of the 4f electrons to the nucleus, these electrons experience a strong spin-orbit interaction.…”

Energy backtransfer and infrared photoresponse in erbium-doped silicon p–n diodes

“…2,5,6,8 Two quenching mechanisms have been identified. First, at temperatures typically above 30 K, Auger quenching takes place, 4 in which an excited Er ion is deexcited by energy transfer to a free electron or hole ͑W A,e and W A,h in Fig.…”

“…[1][2][3][4][5][6][7] Previously, this material has mainly been studied because it provides a means to attain light emission from silicon, a phenomenon that is of great importance in Si-based optoelectronic technology. Indeed, room-temperature photoluminescence ͑PL͒ from Er-doped silicon has been reported, and room-temperature light-emitting diodes have been fabricated.…”