The defects produced in 4H-SiC epitaxial layers by irradiation with a 200 keV H(+) ion beam in the fluence range 6.5 x 10(11)-1.8 x 10(13) ions/cm(2) are investigated by Low Temperature Photoluminescence (LTPL-40 K). The defects produced by ion beam irradiation induce the formation of some sharp lines called "alphabet lines" in the photoluminescence spectra in the 425-443 nm range, due to the recombination of excitons at structural defects. From the LTPL lines intensity trend, as function of proton fluence, it is possible to single out two groups of peaks: the P(1) lines (e, f, g) and the P(2) lines (a, b, c, d) that exhibit different trends with the ion fluence. The P, group normalized yield increases with ion fluence, reaches a maximum at 2.5 x 10(12) ions/cm(2) and then decreases. The P(2) group normalized yield, instead, exhibits a formation threshold at low fluence, then increases until a maximum value at a fluence of 3.5 x 10(12) ions/cm(2) and decreases at higher fluence, reaching a value of 50% of the maximum yield. The behaviour of P(1) and P(2) lines, with ion fluence, indicates a production of point defects at low fluence, followed by a subsequent local rearrangement creating complex defects at high fluence. (C) 2009 Elsevier B.V. All rights reserved.
|Titolo:||Point defects induced in ion irradiated 4H-SiC probed by exciton lines|
|Data di pubblicazione:||2009|
|Appare nelle tipologie:||1.1 Articolo in rivista|