Polarization and temperature dependence of photoluminescence of m-plane GaN grown on γ-LiAlO2 (100) substrate

Abstract

We investigated the polarization and temperature dependence of photoluminescence ͑PL͒ of m-plane GaN grown on ␥-LiAlO 2 ͑100͒ substrate. The calculated electronic band structure with k • p Hamiltonian points out the energy splitting as well as polarization selection originate from the m-plane GaN epilayer under anisotropic strain. The polarization-angle dependence PL spectra are found to be selected from in-plane x-and z-polarized emission, corresponding to T 1 and T 2 transition. And the intensity distribution of the fitting peaks satisfies the Malus' law. An S-shape energy evolution of near band edge peak on temperatures is observed, which originates from the transition between the localized holes and electrons in triangular potentials induced by basal stacking faults. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3204453͔ Spontaneous and piezoelectric polarization along the ͓0001͔ axis of wurtzite GaN and its alloys greatly affect the efficiency of luminescence in GaN-based optoelectronic devices. 1 In order to eliminate these polarization effects, one way is to deposit an m-or a-plane GaN film along unconventional non-polar directions, such as ͓1100͔ ͑Ref. 2-4͒ or ͓1120͔. 5-7 ␥-LiAlO 2 ͑LAO͒ has a tetragonal structure and its ͑100͒ plane exhibits a comparatively small lattice mismatch to GaN ͑1100͒. Since the m-plane GaN was grown by molecular-beam epitaxy on this substrate, 2 the development of nonpolar GaN based optoelectronic devices has attracted much attention. Unlike c-plane GaN, nonpolar GaN usually suffers from anisotropic in-plane strain, which leads to a splitting in the electronic band structure ͑EBS͒. Therefore, understanding the EBS of nonpolar GaN is significant for the application of optoelectronic devices. Previously, optical measurements, such as reflectance, transmission, and photoreflectance, were used to determine the EBS near the ⌫ point and verify the theoretical calculation of the energy splitting of the m-plane GaN. [8][9][10][11] Luminescence properties of a-plane GaN, including temperature and polarization dependent, spatially resolved photoluminescence ͑PL͒ and cathodoluminescence, were also particularly studied. [12][13][14] Recently, the authors reported the splitting and anisotropy of emission light polarization of the m-plane GaN on LAO͑100͒ by using PL measurements. 15 In this letter, we investigate the polarization-angle and temperature dependence of the polarized PL transitions of the m-plane GaN film on LAO͑100͒ in order to explore the evolution of splitting valence band under anisotropic strain conditions.The studied sample of a typical 0.92 m thick m-plane GaN with background electron concentration ϳ2 ϫ 10 18 cm −3 ͑named as sample I͒ was grown on LAO͑100͒ by metalorganic chemical vapor deposition. 4 High-resolution x-ray diffraction technique revealed the m-plane GaN epilayer under biaxial compressive strain of xx = −0.79% and zz = −0.14% with an out-of-plane dilatation yy = 0.38%. 15 An unintentionally doped n-type c-plane GaN with thickness of 2.5 m on ␣-Al 2 O...

Temperature‐Dependent Polarized Photoluminescence from c‐plane InGaN/GaN Multiple Quantum Wells Grown on Stripe‐Shaped Cavity‐Engineered Sapphire Substrate

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High-Brightness Polarized Green InGaN/GaN Light-Emitting Diode Structure with Al-Coated p-GaN Grating

“…Several approaches have been previously proposed to achieve polarized light emission from III-nitride LEDs. − For example, it has been widely reported that a high degree of intrinsic linearly polarized light emission can be obtained from LED structures grown on nonpolar/semipolar substrates. , However, it suffers from the high cost of nonpolar/semipolar substrates, as well as the high density of basal stacking faults and threading dislocations in the material . Other reports have demonstrated that highly polarized luminescence can be obtained through the integration of nanostructures, such as metal gratings, combined dielectric/metal structures, and photonic crystals .…”