Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Engineering
Piezoelectric Effects On The Optical Properties Of Gan/Alxga1−Xn Multiple Quantum Wells, H. S. Kim, J. Y. Lin, H. X. Jiang, W. W. Chow, A. Botchkarev, Hadis Morkoç
Piezoelectric Effects On The Optical Properties Of Gan/Alxga1−Xn Multiple Quantum Wells, H. S. Kim, J. Y. Lin, H. X. Jiang, W. W. Chow, A. Botchkarev, Hadis Morkoç
Electrical and Computer Engineering Publications
Piezoelectric effects on the optical properties of GaN/AlGaN multiple quantum wells(MQWs) have been investigated by picosecond time-resolvedphotoluminescence(PL)measurements. For MQWs with well thicknesses 30 and 40 Å, the excitonic transition peak positions at 10 K in continuous wave (cw) spectra are redshifted with respect to the GaN epilayer by 13 and 45 meV, respectively. The time-resolvedPL spectra of the 30 and 40 Å well MQWs reveal that the excitonic transition is in fact blueshifted at early delay times due to quantum confinement of carriers. The spectral peak position shifts toward lower energies as the delay time increases and becomes redshifted at …
Deep Centers In N-Gan Grown By Reactive Molecular Beam Epitaxy, Z.-Q. Fang, D. C. Look, W. Kim, Z. Fan, A. Botchkarev, Hadis Morkoç
Deep Centers In N-Gan Grown By Reactive Molecular Beam Epitaxy, Z.-Q. Fang, D. C. Look, W. Kim, Z. Fan, A. Botchkarev, Hadis Morkoç
Electrical and Computer Engineering Publications
Deep centers in Si-doped n-GaN layers grown by reactive molecular beam epitaxy have been studied by deep-level transient spectroscopy as a function of growth conditions. Si-doped GaN samples grown on a Si-doped n+-GaN contact layer at 800 °C show a dominant trap C1 with activation energyET=0.44 eV and capture cross-section σT=1.3×10−15 cm−2, while samples grown at 750 °C on an undoped semi-insulating GaN buffer show prominent traps D1and E1, with ET=0.20 eV and σT=8.4×10−17 cm2, and ET=0.21 eV and σT=1.6×10−14 cm2, respectively. Trap E1 is believed to be related to a N-vacancy defect, since the Arrhenius signature for E1 is …
Plasma Heating In Highly Excited Gan/Algan Multiple Quantum Wells, K. C. Zeng, R. Mair, J. Y. Lin, H. X. Jiang, W. W. Chow, A. Botchkarev, Hadis Morkoç
Plasma Heating In Highly Excited Gan/Algan Multiple Quantum Wells, K. C. Zeng, R. Mair, J. Y. Lin, H. X. Jiang, W. W. Chow, A. Botchkarev, Hadis Morkoç
Electrical and Computer Engineering Publications
Time-resolvedphotoluminescence(PL)spectroscopy was used to investigate carrier distributions in a GaN/AlGaN multiple quantum well(MQW) sample under high excitation intensities necessary to achieve lasing threshold. Room temperaturePL spectra showed optical transitions involving both confined and unconfined states in the quantum well structure. Analysis of the experimental results using a microscopic theory, indicates that at high excitation the carrier distributions are characterized by plasma temperatures which are significantly higher than the lattice temperature. The implications of our findings on GaN MQW laser design are also discussed.
Deep Level Defects In N-Type Gan Grown By Molecular Beam Epitaxy, C. D. Wang, L. S. Yu, S. S. Lau, E. T. Yu, W. Kim, A. E. Botchkarev, Hadis Morkoç
Deep Level Defects In N-Type Gan Grown By Molecular Beam Epitaxy, C. D. Wang, L. S. Yu, S. S. Lau, E. T. Yu, W. Kim, A. E. Botchkarev, Hadis Morkoç
Electrical and Computer Engineering Publications
Deep-level transient spectroscopy has been used to characterize electronic defects in n-type GaN grown by reactive molecular-beam epitaxy. Five deep-level electronic defects were observed, with activation energiesE1=0.234±0.006, E2=0.578±0.006, E3=0.657±0.031, E4=0.961±0.026, and E5=0.240±0.012 eV. Among these, the levels labeled E1, E2, and E3are interpreted as corresponding to deep levels previously reported in n-GaN grown by both hydride vapor-phase epitaxy and metal organic chemical vapor deposition. Levels E4 and E5do not correspond to any previously reported defect levels, and are characterized for the first time in our studies.
Optical Modes Within Iii-Nitride Multiple Quantum Well Microdisk Cavities, R. A. Mair, K. C. Zeng, J. Y. Lin, H. X. Jiang, B. Zhang, L. Dai, A. Botchkarev, W. Kim, Hadis Morkoç, M. A. Khan
Optical Modes Within Iii-Nitride Multiple Quantum Well Microdisk Cavities, R. A. Mair, K. C. Zeng, J. Y. Lin, H. X. Jiang, B. Zhang, L. Dai, A. Botchkarev, W. Kim, Hadis Morkoç, M. A. Khan
Electrical and Computer Engineering Publications
Optical resonance modes have been observed in optically pumped microdisk cavitiesfabricated from 50 Å/50 Å GaN/AlxGa1−xN(x∼0.07) and 45 Å/45 Å InxGa1−xN/GaN(x∼0.15)multiple quantum well structures. Microdisks, approximately 9 μm in diameter and regularly spaced every 50 μm, were formed by an ion beametch process. Individual disks were pumped at 300 and 10 K with 290 nm laser pulses focused to a spot size much smaller than the disk diameter. Optical modes corresponding to (i) the radial mode type with a spacing of 49–51 meV (both TE and TM) and (ii) the Whispering Gallery mode with a spacing of 15–16 meV were …
Effect Of Ammonia Flow Rate On Impurity Incorporation And Material Properties Of Si-Doped Gan Epitaxial Films Grown By Reactive Molecular Beam Epitaxy, Wook Kim, A. E. Botchkarev, H. Morkoç, Z.-Q. Fang, D. C. Look, David J. Smith
Effect Of Ammonia Flow Rate On Impurity Incorporation And Material Properties Of Si-Doped Gan Epitaxial Films Grown By Reactive Molecular Beam Epitaxy, Wook Kim, A. E. Botchkarev, H. Morkoç, Z.-Q. Fang, D. C. Look, David J. Smith
Electrical and Computer Engineering Publications
Effect of ammonia flow rate on the impurity incorporation and material properties of Si-doped GaN films grown by reactive molecular beam epitaxy (RMBE) process is discussed. It appears that the ammonia flow rate has a marginal effect on the incorporation of impurities into the Si-doped GaN films except there was a little decrease in O and Si with increasing ammonia flow rate when the Si concentration in the film is higher than 1018 cm−3. Electron Hall mobility of Si-doped GaN films grown by RMBE varies with ammonia flow rate used during film growth. From deep level transient spectroscopy(DLTS) measurements for …