Dislocation Luminescence in Wurtzite GaN

Abstract

The 364 nm PL-system in GaN is attributed to the formation of dislocation excitons and charged dislocation excitons on c-axis screw dislocations. The binding energy for the dislocation exciton, charged dislocation exciton and a hole on the screw dislocation were determined as 35 meV, 7 meV and 65 meV respectively, in accord with experiment.

Unusual luminescence lines in GaN

“…12,16 Sometimes a doublet structure of this peak was observed. 15,18,20 The relative intensity of this peak increased after annealing, especially in water vapor atmosphere. 36 It was noted in Ref.…”

“…14,18,21 Others attributed the 3.42 eV peak to a transition from a donor to the valence band where the donor was assumed to be oxygen. 12,13 Some investigators suggested that the 3.42 eV peak is related to structural defects, 10,[15][16][17][18][19][20] in particular to cubic inclusions or stacking faults in the wurtzite GaN 10,18,19 or to c-axis screw dislocations. 20 The 3.42 eV peak, denoted in this study as Y 2 , appeared in many of our as-grown GaN samples with Ga and sometimes N polarity.…”

“…For example, the commonly observed 3.42 eV peak [12][13][14][15][16][17][18][19][20][21] has been attributed to recombination between electrons bound to oxygen donors and free holes, 12,13 DAP-type transitions involving a very shallow unidentified acceptor, 14 and exciton bound to structural defects, 10,[15][16][17][18][19][20] in particular to stacking faults 17,19 and c-axis screw dislocations. 20 Even less is known about the other peaks. The purpose of this article is to catalogue these unusual PL lines in GaN and establish their characteristics.…”

On the luminescence of freshly introduced a-screw dislocations in low-resistance GaN

“…For grown in dislocations, luminescence lines were reported at 3.21 [11] and 3.4 eV [6]. For arrays of dislocations introduced by plastic deformation at ele vated temperatures, emission lines at 1.8, 1.9, 2.4 [12], and 2.9 eV [13] were detected.…”

“…Experimental data on the effect of dislocations on GaN luminescence, obtained until recently revealed both the nonradiative nature of recombination at dis locations and the appearance of new spectral lumines cence bands [6][7][8][9][10].…”