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Full-Text Articles in Engineering
Correlation Between Si Doping And Stacking Fault Related Luminescence In Homoepitaxial M-Plane Gan, S. Khromov, B. Monemar, Vitaliy Avrutin, Hadis Morkoç, L. Hultman, G. Pozina
Correlation Between Si Doping And Stacking Fault Related Luminescence In Homoepitaxial M-Plane Gan, S. Khromov, B. Monemar, Vitaliy Avrutin, Hadis Morkoç, L. Hultman, G. Pozina
Electrical and Computer Engineering Publications
Si-doped GaN layers grown by metal organic vapor phase epitaxy on m-plane GaN substrates were investigated by low-temperature cathodoluminescence (CL). We have observed stacking fault (SF) related emission in the range of 3.29–3.42 eV for samples with moderate doping, while for the layers with high concentration of dopants, no CL lines related to SFs have been noted. Perturbation of the SF potential profile by neighboring impurity atoms can explain localization ofexcitons at SFs, while this effect would vanish at high doping levels due to screening.
Growth Optimization And Structural Analysis For Ferromagnetic Mn-Doped Zno Layers Deposited By Radio Frequency Magnetron Sputtering, M. Abouzaid, P. Ruterana, C. Liu, H. Morkoç
Growth Optimization And Structural Analysis For Ferromagnetic Mn-Doped Zno Layers Deposited By Radio Frequency Magnetron Sputtering, M. Abouzaid, P. Ruterana, C. Liu, H. Morkoç
Electrical and Computer Engineering Publications
The effect of the deposition temperature on the crystalline quality of (Zn,Mn)O is investigated in thin films prepared by radio frequency magnetronsputtering on c-plane sapphire and GaN substrates. The layers are made of a 0.5μm Mn-doped layer towards the surface on top of a 150nm pure ZnO buffer. Depending on the deposition temperature, the layers can exhibit a columnar structure; the adjacent domains are rotated from one another by 90°, putting [101¯0]and [11¯20] directions face to face. At high Mn concentration the columnar structure is blurred by the formation of Mn rich precipitates. Only one variety of domains is observed …
Transient Photovoltage In Gan As Measured By Atomic Force Microscope Tip, M. A. Reshchikov, S. Sabuktagin, D. K. Johnstone, H. Morkoç
Transient Photovoltage In Gan As Measured By Atomic Force Microscope Tip, M. A. Reshchikov, S. Sabuktagin, D. K. Johnstone, H. Morkoç
Electrical and Computer Engineering Publications
We studied restoration of the band bending at the surface of undoped GaN layers after illumination with above-bandgap light. The photovoltage saturated with illumination at about 0.2–0.3 eV at room temperature, although the upward band bending for GaN in the dark is of the order of 1 eV. We attribute the photovoltage effect to charging of the surface states, the density of which is estimated at about 10^12 cm^−2. Restoration of the barrier after a light pulse is simulated by a phenomenological model whereby the acceptorlike surface states are emptied of electrons under illumination and filled back in dark due …
Long-Lasting Photoluminescence In Freestanding Gan Templates, Michael A. Reshchikov, M. Zafar Iqbal, Hadis Morkoç, S. S. Park, K. Y. Lee
Long-Lasting Photoluminescence In Freestanding Gan Templates, Michael A. Reshchikov, M. Zafar Iqbal, Hadis Morkoç, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
We studied time-resolvedphotoluminescence(PL) over a temporal range 10−6–103 s in high-purity freestanding GaN templates. Red, yellow, green, blue, and shallow donor–acceptor emission bands can be resolved in the PLspectrum. Observation of luminescence long after the excitation is switched off is a striking feature of our study. The persistent PL observed for all above bands, except for the green band, is primarily attributed to the donor–acceptor-pair-type recombination. An unusually slow, nonexponential decay of radiative transitions from the conduction band to the shallow acceptor was also observed, pointing to some additional mechanism for the persistent PL. Possible role of the surface states …