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RISS 인기검색어
- 검색키워드
- 저자 : M. Heuken (검색결과 4 건)
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D. R. Hang,Mitch M. C. Chou,J. L. Lin,M. Heuken 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
We investigate the optical properties of m-plane InGaN/GaN multiple quantum wells (MQWs) grown on LiAlO2 substrates by using metal organic vapor phase epitaxy (MOVPE). Polarizationdependent photoluminescence (PL) measurements have been employed to study the optical emission characteristics. We demonstrate that the PL emission has a large polarization anisotropy, which can be attributed to the anisotropic in-plane strain. The degree of polarization is studied as a function of temperature, and the dependence can be explained by using the modified band structure model. The energy splitting of the two uppermost valence bands is obtained from polarized PL spectroscopy and is in good agreement with the activation energy deduced from the Arrhenius relationship. From the excitation-dependent PL measurements, we found the optical emission not to be influenced by the polarization-induced electric field. Our results are important for the design and the fabrication of non-polar InGaN/GaN MQW polarization-sensitive optical devices We investigate the optical properties of m-plane InGaN/GaN multiple quantum wells (MQWs) grown on LiAlO2 substrates by using metal organic vapor phase epitaxy (MOVPE). Polarizationdependent photoluminescence (PL) measurements have been employed to study the optical emission characteristics. We demonstrate that the PL emission has a large polarization anisotropy, which can be attributed to the anisotropic in-plane strain. The degree of polarization is studied as a function of temperature, and the dependence can be explained by using the modified band structure model. The energy splitting of the two uppermost valence bands is obtained from polarized PL spectroscopy and is in good agreement with the activation energy deduced from the Arrhenius relationship. From the excitation-dependent PL measurements, we found the optical emission not to be influenced by the polarization-induced electric field. Our results are important for the design and the fabrication of non-polar InGaN/GaN MQW polarization-sensitive optical devices
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Da-Ren Hang,M. Heuken,M.C. Chou,M.H. Hsieh 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
We study the influence of a buffer layer on the optical properties of InGaN/GaN multiple quantum wells (MQWs) grown on silicon substrates by using metalorganic vapor phase epitaxy. To overcome the large lattice mismatch and the difference in the thermal expansion coefficients by which a high dislocation density occurs, we grow the MQWs on an advanced buffer structure consisting of low-temperature (LT) AlN and a high-temperature (HT) AlN/AlGaN/GaN stack. The Raman spectra confirm that the biaxial tensile strain is reduced by the insertion of the alternating LT and HT buffer layers. Moreover, we find the room-temperature internal quantum efficiency can be improved. Our results suggest that the enhanced optical performance comes from the reduced number of nonradiative recombination centers brought about by the LT and HT composite buffer layers.
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Temperature Dependence of the Stokes Shift in Tensile InGaN/GaN MQWs with Advanced Buer Layers
D. R. Hang,M. M. C. Chou,M. H. Hsieh,M. Heuken 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3
The influence of buer layers on the optical absorption and the emission properties of tensile InGaN/GaN multiple quantum wells (MQWs) has been studied. Here, sets of buffer structures consisting of low-temperature AlN and high-temperature AlN/AlGaN/GaN stacks have been employed to compensate for the detrimental eects brought about by the large lattice mismatch and by the difference in thermal expansion coefficients when silicon substrates are used. We found the biaxial tensile strain could be reduced and that the internal quantum efficiency could be considerably improved. Moreover, the Stokes shift could be reduced and its temperature variation became stabilized. The underlying mechanism is mainly due to the quantum confined Stark effect while the contribution from the localization effect is relatively small in our tensile InGaN/GaN MQWs.
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Terbium Implanted AlN And Photoluminescence Properties
F. Lu,A. A. Alam,M. Heuken,R. Carius 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
200 nm AlN ¯lms were grown on Si (111) by metalorganic chemical vapor deposition. X-ray diraction shows that the AlN ¯lms are polycrystalline. The AlN ¯lms were doped by ion implan- tation of Tb to the peak atomic concentration from 0.2 % to 2 %. Post annealing was performed at 850 ±C for 30 min. The Tb distributions were measured by RBS/channeling technique. Blue-green photoluminescence from annealed Tb implanted AlN ¯lms have been observed at room tempera-ture. Photoluminescence intensity and lifetime from Tb:AlN versus Tb concentrations have been measured and discussed.
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