Prismatic stacking faults in epitaxially laterally overgrown GaN

Abstract

We report on the presence of optically active stacking faults on basal and prismatic planes in epitaxially laterally overgrown GaN (ELOG) on {112¯2} facets. The structure of the faults has been analyzed using diffraction contrast electron microscopy. We show that stacking faults on {112¯0} prismatic planes involve a lattice displacement of 12⟨11¯01⟩, parallel to the fault plane. They appear as jogs connecting basal-plane stacking faults, the latter with a lattice displacement of 16⟨202¯3⟩. These faults are observed only in the laterally overgrown regions that grow on {112¯2} planes, which indicates that the stacking fault formation is closely related to the orientation of the growth surface. Possible formation mechanisms of these faults are discussed. Direct correlation between TEM and cathodoluminescence shows that these prismatic-plane and basal-plane stacking faults are optically active with light emission at 3.30 and 3.41eV, respectively.

Correlation between Si doping and stacking fault related luminescence in homoepitaxial m-plane GaN

“…Additionally, three rather narrow emission lines with relative intensities depending on samples and positions have been found in the region of defect luminescence: at $3.42 (SF1), at $3.39 (SF2), and at $3.37 eV (SF3). The emission within the range of 3.39-3.42 eV was previously identified as being related to BSF, [7][8][9][10]16 while the 3.37 eV peak is close to the feature at 3.34 eV related to PSFs in heteroepitaxial a-plane GaN. 7 The origin of these lines is in accordance with these identifications as it is confirmed by spatially resolved CL data presented in Fig.…”

“…SFs of different geometries can sometimes be optically active and may lead to several features in the luminescence spectra in the region of 3.29-3.41 eV as was reported for the heteroepitaxial undoped GaN grown in a-and m-directions. [7][8][9][10] In mature undoped or n-type doped polar GaN layers, the SF density is low and can hardly be considered as a problem for electronic and optoelectronic devices. Correspondingly, in such samples, usually no SF-associated emission is present in the luminescence spectra.…”

Optical and structural studies of homoepitaxially grown m-plane GaN

“…[8][9][10][11] Recently, we also observed SFs in c-plane homoepitaxial GaN doped with Mg, which is the only viable p-type dopant for this material, thus showing that Mg doping can facilitate SF creation in polar GaN. Such samples have demonstrated metastability of the acceptor bound excitons (ABEs) 12,13 and SF-related luminescence at low temperatures.…”

Luminescence related to high density of Mg-induced stacking faults in homoepitaxially grown GaN

“…Here 1101 parallel to the fault plane. 14 Since it is clear that Mg doping causes the SF formation in the GaN layer, it is interesting to know the relative position of the Mg atom with respect to a nearby SF. In order to study that, EDX-scan profiles and corresponding STEM images of basal-plane SFs were performed.…”