Optical anisotropy of excitons in strained GaN epilayers grown along the 〈101¯0〉 direction

Recombination of free and bound excitons in GaN

“…In such a case, however, the c-axis is lying in the growth plane and although the splitting of the exciton states is still governed by the C 2v crystal symmetry the polarization dependence of the reflectance and PL spectra, which reflects the oscillator strength of different exciton states, is more complicated [34][35][36].…”

Effects of strain on the band structure of group-III nitrides

“…The applicability of such a description has been demonstrated in measurements of the optical transition energies for GaN epilayers with residual strain. [23][24][25] To quantify the strain effects for InGaN or AlGaN alloys, accurate deformation potential parameters for all three nitrides are needed.…”

“…Uncertainties in the results of the studies that use this approximation are thus to be expected. [25][26][27]40 Another complication is that the determination of the out-of-plane strain component depends on the numerical values of the elastic stiffness constants. The values of these constants also exhibit a lot of scatter.…”

Reduction of bound‐state and nonradiative defect densities in nonpolar (11&2macr;0) AlGaN/GaN quantum wells by the use of lateral epitaxial overgrowth technique

“…The OR spectra of the sample grown on LEO-GaN exhibited distinct reflectance anomalies at 3.500 and 3.521 eV for the light polarization E perpendicular to the c-axis (E⊥c), and at 3.508 and 3.521 eV for E parallel to the c-axis (E//c), which are due to the excitonic transitions in the underlying GaN. The energy and polarization were different from those of A, B, and C transitions in strain-free GaN, reflecting the change in crystal symmetry from C 6v to C 2v due to the anisotropic strains [8,9]. The strains were quantified by X-ray diffraction measurements to be +0.10, +0.02, and -0.24 % along [11][12][13][14][15][16][17][18][19][20], , and [0001] directions, respectively, where minus and plus signs represent compressive and tensile, respectively.…”

“…In this article, improvements in the optical properties of (11-20) Al x Ga 1-x N/GaN multiple QWs (MQWs) are demonstrated by the use of GaN templates prepared by LEO (LEO-GaN) [7]. Polarized optical reflectance (OR) and photoluminescence (PL) spectra of LEO-GaN exhibited excitonic transitions, which obeyed the polarization selection rules for anisotropically-strained GaN [8,9]. Results of time-resolved PL (TRPL) measurements suggested that the improved η int of the MQWs on LEO-GaN was due to the increase in τ nr and the decrease in radiative lifetime (τ r ).…”