Effects of material growth technique and Mg doping on Er3+ photoluminescence in Er-implanted GaN

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopie s have been carried out at 6 K on the similar to 1540 nm I-4(13/2)-I-4(15/2 ) emissions of Er3+ in Er-implanted and annealed GaN. These studies reveale d the existence of multiple Er3+ centers and associated PL spectra in Er-im planted GaN films grown by metalorganic chemical vapor deposition, hydride vapor phase epitaxy, and molecular beam epitaxy. The results demonstrate th at the multiple Er3+PL centers and below-gap defect-related absorption band s by which they are selectively excited are universal features of Er-implan ted GaN grown by different techniques. It is suggested that implantation-in duced defects common to all the GaN samples are responsible for the Er site distortions that give rise to the distinctive, selectively excited Er3+PL spectra. The investigations of selectively excited Er3+PL and PLE spectra h ave also been extended to Er-implanted samples of Mg-doped GaN grown by var ious techniques. In each of these samples, the so-called violet-pumped Er3PL band and its associated broad violet PLE band are significantly enhanced relative to the PL and PLE of the other selectively excited Er3+PL centers . More importantly, the violet-pumped Er3+PL spectrum dominates the above-g ap excited Er3+PL spectrum of Er-implanted Mg-doped GaN, whereas it was uno bservable under above-gap excitation in Er-implanted undoped GaN. These res ults confirm the hypothesis that appropriate codopants can increase the eff iciency of trap-mediated above-gap excitation of Er3+ emission in Er-implan ted GaN. (C) 2001 American Institute of Physics.