Absorption Coefficient and Refractive Index of GaN, AIN and AlGaN Alloys
ABSTRACT The design of optoelectronic devices fabricated from III-nitride materials is aided by knowledge of the refractive index and absorption coefficient of these materials. The optical properties of GaN, AIN and A1GaN grown by MOVPE on sapphire substrates were investigated by means of transmittance and reflectance measurements. Thin (less than 0.5 μm) single crystal films were employed to insure that transmission measurements could be obtained well above the optical band gap. The influence of alloy broadening on the absorption edge was investigated by using a series of AlGaN alloy samples with a range of Al compositions. The optical absorption coefficient above the band gap was obtained for AIGaN having up to 38% Al composition. The refractive index below the band gap was determined for the same series of samples. These properties provide information critical to the optimal design of solar blind detectors or other optoelectronic devices.
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ABSTRACT: Light extraction efficiency of GaN-based LEDs as functions of chip dimensions, absorption coefficients and package for both conventional one and Thin-GaN are analyzed based on Monte-Carlo ray tracing.05/2006;
- International Journal of High Speed Electronics and Systems 11/2011; 14(01).
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ABSTRACT: The optical pumping spectra of InGaN/GaN single quantum well structures with high indium content after thermal annealing were analyzed at room temperature. Redshift of the peak position in the optical pumping spectra was observed after the samples were annealed for 0.5 h at 700 °C. However, blueshift of the peak position was shown after the samples were annealed for 1 and for 2 h. Three mechanisms of band structure deformation due to the thermal treatments have been proposed. The redshift of the peaks might be due to the reduction of the inhomogeneity of the indium content in quantum well. The blueshift of the peaks might originate from the strain relaxation resulting in the reduction of the piezoelectric field or/and the interfacial interdiffusion of In and Ga atoms between the well and barrier.Solid-State Electronics 08/2002; 46(8):1123-1126. · 1.51 Impact Factor