Absorption Coefficient and Refractive Index of GaN, AIN and AlGaN Alloys

1998 ◽  
Vol 537 ◽  
Author(s):  
J. F. Muth ◽  
J. D. Brown ◽  
M. A. L. Johnson ◽  
Zhonghai Yu ◽  
R. M. Kolbas ◽  
...  
Keyword(s):  
Refractive Index ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Optoelectronic Devices ◽  
Optical Absorption Coefficient ◽  
Solar Blind ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Transmission Measurements ◽  
Reflectance Measurements

AbstractThe 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.

scholarly journals Absorption Coefficient and Refractive Index of GaN, AlN and AlGaN Alloys

1999 ◽  
Vol 4 (S1) ◽  
pp. 502-507 ◽  
Author(s):  
J. F. Muth ◽  
J. D. Brown ◽  
M. A. L. Johnson ◽  
Zhonghai Yu ◽  
R. M. Kolbas ◽  
...  
Keyword(s):  
Refractive Index ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Optoelectronic Devices ◽  
Optical Absorption Coefficient ◽  
Solar Blind ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Transmission Measurements ◽  
Reflectance Measurements

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, AlN and AlGaN 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 AlGaN 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.

INTERSUBBAND OPTICAL ABSORPTION COEFFICIENTS AND REFRACTIVE INDEX CHANGES OF AN ELLIPSOIDAL FINITE POTENTIAL QUANTUM DOT

2010 ◽  
Vol 19 (01) ◽  
pp. 131-143 ◽  
Author(s):  
G. REZAEI ◽  
M. R. K. VAHDANI ◽  
M. BARATI
Keyword(s):  
Refractive Index ◽  
Light Intensity ◽  
Optical Absorption ◽  
Quantum Dot ◽  
Absorption Coefficient ◽  
Optical Absorption Coefficient ◽  
Matrix Formalism ◽  
Ellipsoidal Quantum Dot ◽  
Index Changes ◽  
Intersubband Optical Absorption

Intersubband optical absorption coefficient and refractive index changes of a weakly prolate ellipsoidal quantum dot, using the compact-density matrix formalism and iterative method, are investigated. In this regard, the linear and nonlinear intersubband optical absorption coefficient and refractive index changes of a GaAs / Al x Ga 1-x As ellipsoidal quantum dot, as functions of the dot radius, ellipticity constant, stoichiometric ratio and incident light intensity are calculated. The results indicate that absorption coefficient and refractive index changes strongly depend on the light intensity, size and geometry of the dot and structure parameters such as aluminium concentration in GaAs / Al x Ga 1-x As structures.

scholarly journals Effect of gamma irradiation on structural, morphological and optical properties of p-quaterphenyl thin films

2018 ◽  
Vol 14 (2) ◽  
pp. 5624-5637
Author(s):  
A.A. Attia ◽  
M.M. Saadeldin ◽  
K. Sawaby
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Surface Morphology ◽  
Absorption Coefficient ◽  
Gamma Irradiation ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation Method ◽  
Single Oscillator Model

Para-quaterphenyl thin films were deposited onto glass and quartz substrates by thermal evaporation method. p-quaterphenyl thin films wereexposed to gamma radiation of Cobat-60 radioactive source at room temperature with a dose of 50 kGy to study the effect of ?-irradiation onthe structure and the surface morphology as well as the optical properties of the prepared films. The crystalline structure and the surface morphology of the as-deposited and ?-irradiated films were examined using the X-ray diffraction and the field emission scanning electron microscope. The optical constants (n & k) of the as-deposited and ?-irradiated films were obtained using the transmittance and reflectance measurements, in the wavelength range starting from 250 up to 2500 nm. The analysis of the absorption coefficient data revealed an allowed direct transition with optical band gap of 2.2 eV for the as-deposited films, which decreased to 2.06 eV after exposing film to gamma irradiation. It was observed that the Urbach energy values change inversely with the values of the optical band gap. The dispersion of the refractive index was interpreted using the single oscillator model. The nonlinear absorption coefficient spectra for the as-deposited and ?-irradiated p-quaterphenyl thin films were obtained using the linear refractive index.

Nonlinear Intersubband Optical Absorption Coefficient and Refractive Index Changes in Asymmetric Parabolic Double Quantum Wells

2017 ◽  
Vol 6 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Menberu Mengesha Woldemariam
Keyword(s):  
Refractive Index ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Quantum Wells ◽  
Optical Absorption Coefficient ◽  
Double Quantum ◽  
Absorption Coefficients ◽  
Total Change ◽  
Left Handed ◽  
Index Changes

The change in optical absorption coefficients and refractive index in GaAs-AlGaAs asymmetric parabolic double quantum wells (DQWs) with applied electric field are studied in detail. Analytical expressions for the linear, nonlinear and total intersubband absorption coefficient and refractive index changes are obtained by using compact density matrix approach. It is found that the magnitude of the nonlinear part of the change in refractive index and absorption coefficients are larger than the linear part in the given frequency region. The value of the total change in refractive index is negative and the asymmetric DQWs becomes left handed media. This property is of great importance for metamaterials science and can contribute substantially to the present search for simple and inexpensive left handed media. Moreover the negative value of the total change in absorption coefficient may be used for developing optical device such as maser at different frequency regime.

scholarly journals First Principles Study on Electronic Structure and Optical Properties of PMMA Doped InSb–Mn Alloy Polymer Matrix Composite

2022 ◽  
Vol 2022 ◽  
pp. 1-6
Author(s):  
Dhanabalakrishnan Kovilpalayam Palaniswamy ◽  
Pandiyan Arumugan ◽  
Ravindiran Munusami ◽  
A Chinnasamy ◽  
S. Madhu ◽  
...  
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Electronic Structure ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Optical Conductivity ◽  
First Principles ◽  
Dft Method ◽  
Optical Absorption Coefficient ◽  
Group Iii

InSb the group III-V semiconductor with narrow band gap is combined with Mn in various concentrations and that InSb–Mn alloy is doped with poly methyl methacrylate (PMMA). The optical properties and electronic structure of ternary InSb–Mn alloy with PMMA are investigated by first principles calculations using the DFT method. Varying Mn concentrations play an important role in the improvement of the absorption coefficient and optical conductivity. It is observed that the band gap of InSb–Mn: PMMA decreases monotonously with the increase in Mn concentration. Optical properties of InSb–Mn: PMMA, such as the optical absorption coefficient and optical conductivity, are greater than those of pure InSb. InSb–Mn: PMMA alloy is doped with PMMA polymer in order to make a thin film as PMMA is a transparent thermoplastic polymer. These results suggest a promising application of InSb–Mn: PMMA thin film in optoelectronics when the InSb doping is 24% with improved conductivity when compared with other doping ratios. This states the optimum doping ratio and the major finding in the carried out research based on modelling and simulation.

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