Unusual Polarization Dependence of Dislocation‐Related Luminescence in n‐GaN

Dislocations introduced by Vickers tip microindentation of an a-plane free-standing semi-insulating Fe-doped GaN halide vapor phase epitaxy (HVPE) crystal were investigated by means of cathodoluminescence and scanning transmission electron microscopy techniques. Detailed combined analyses of both spectral properties and the core structure of the introduced a-screw dislocations revealed that Fe-doped GaN exhibit not only dislocation-bound emission at ∼3.35 eV of perfect a-screw dislocations previously found in such kind of samples but also luminescent bands at 3.1–3.2 and 3.3 eV due to dissociated a-screw dislocations and extended dislocation nodes previously observed only in low-resistance n-GaN. For the first time, all these luminescent bands were observed together in the same sample. Structural studies revealed the coexistence of the dislocations with the dissociated and the perfect core as well as with extended dislocation nodes, thus establishing a correlation between previously observed luminescence bands and a fine dislocation core structure.

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Fine core structure and spectral luminescence features of freshly introduced dislocations in Fe-doped GaN

Shapenkov

Vyvenko

Ubyĭvovk

et al. 2022

Journal of Applied Physics

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Characteristic emission from quantum dot-like intersection nodes of dislocations in GaN

Shapenkov

Vyvenko

Schmidt

et al. 2021

J. Phys.: Conf. Ser.

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Freshly introduced a-screw dislocations in gallium nitride are an effective source of ultraviolet radiation, characterized by intense emission of narrow luminescence doublet lines in the spectral range of 3.1-3.2 eV. Furthermore, an additional narrow spectral line with an energy of 3.3 eV has been found at the points of intersection of such dislocations, where extended dislocation nodes were formed. In this communication, we report on the spectral properties of the characteristic luminescence of such nodes, which were obtained for the (0001) gallium nitride samples with dislocations introduced by nanoindentation. The spectral position of the dislocation-related luminescence doublet experiences a redshift with increasing distance from the indentation site. It follows the spectral shift of the excitonic near-bandgap emission, associated with stress relaxation. The luminescence of the intersection points exhibits a similar tendency. At certain local positions, its doublet fine structure is observed, which has a spectral linewidth of the order of or even less than that of the exciton. In this case, the spectral splitting between components of the doublet varies irregularly depending on the position of the exciton (i.e., on the mechanical stress). We see a clear indication of quantum dot-like emission. The fine structure of the luminescence of the intersection points can be easily explained by the energy dependence of emission on their size, as well as on their density, in particular, by the formation of paired nodes, which were previously observed in experiments in a transmission electron microscope.

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Carrier Dynamics in InGaN/GaN-Based Green LED under Different Excitation Sources

Chen

et al. 2021

Crystals

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The excitation power and temperature dependence of the photoluminescence (PL) and electroluminescence (EL) spectra were studied in green InGaN/GaN multiple quantum well (MQW)-based light-emitting diodes (LED). An examination of the PL-325, PL-405, and EL spectra at identical optical or electrical generation rates at room temperature showed that the normalized spectra exhibited different characteristic peaks. In addition, the temperature behavior of the peak energy was S-shaped for the PL-405 spectrum, while it was V-shaped for the EL spectrum. These measurement results demonstrate that the excitation source can affect the carrier dynamics about the generation (injection), transfer, and distribution of carriers.

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Unusual Polarization Dependence of Dislocation‐Related Luminescence in n‐GaN

Cited by 3 publications

References 18 publications

Fine core structure and spectral luminescence features of freshly introduced dislocations in Fe-doped GaN

Fine core structure and spectral luminescence features of freshly introduced dislocations in Fe-doped GaN

Characteristic emission from quantum dot-like intersection nodes of dislocations in GaN

Carrier Dynamics in InGaN/GaN-Based Green LED under Different Excitation Sources

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