Optical Doping of Nitrides by Ion Implantation

Abstract

A series of rare earth elements (RE) were implanted in GaN epilayers to study the lattice site location and optical activity. Rutherford backscattering spectrometry in the channeling mode(RBS/C) was used to follow the damage behavior in the Ga sublattice and the site location of the RE. For all the implanted elements (Ce, Pr, Dy, Er, and Lu) the results indicate the complete substitutionality on Ga sites after rapid thermal annealing at 1000 o C for 2 min. The only exception occurs for Eu that occupies a Ga displaced site. Annealing at 1200 o C in nitrogen atmosphere at a pressure of 1GPa is necessary to achieve the complete recovery of the damage in the samples. After annealing the recombination processes of the implanted samples were studied by above and below band gap excitation. For Er implanted samples besides the 1.54 m emission green and red emissions are also observed. Red emissions from 5 D0 7 F2 and 3 P0 3 F2 transitions were found in Eu and Pr implanted samples even at room temperature.

High pressure annealing of Europium implanted GaN

“…The widths of the Eu-and the Ga-scans are seen to be similar for both directions indicating that Eu is incorporated on substitutional Ga-sites. Eu is often seen to incorporate slightly displaced from the perfect Ga-site 14,15 ; however, in this case, due to the high minimum yield of the Eu scans, it is difficult to determine a value for this displacement. In fact, the fits shown in Fig.…”

High intensity red emission from Eu doped GaN powders

“…The lattice constants of a pure GaN powder sample without Eu doping grown at 1000 ºC are found to be smaller (a = 3.186 Å and c = 5.178 Å) than those of sample no.6 grown at the same temperature with Eu doping. It is well known that the majority of the Eu 3+ ions occupy the substitutional Ga 3+ trivalent ionic states when incorporated in GaN [13]. Greater incorporation of Eu increases the lattice constants, as Eu is much bigger in size than Ga, with a corresponding increase in bond-length [14].…”

Lattice location and optical activation of rare earth implanted GaN

“…Those who studied luminescence from samples implanted at varying doses [14,18,19,22,23,[49][50][51][52][53] generally found that implantations in the 1-5×10 15 cm −2 range gave stronger luminescence than lower doses. At higher fluences the inability to regrow a crystalline GaN layer from the amorphous state presents a limit.…”