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ZnO Single Crystals (zno + single_crystal)
Selected AbstractsElectro-optic property of ZnO:Mn epitaxial filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008T. Oshio Abstract Mn doping effect on the dielectric and electro-optic (E-O) property of ZnO epitaxial films was studied. The leakage current of the ZnO film is drastically decreased by doping Mn with the concentration of 3-5 at%. Although, ZnO: 4 at% Mn with the lowest leakage current has the largest frequency dispersion of birefringence shift (, n) at 1 kHz, and its E-O coefficient (rc) was larger than that of ZnO single crystal. It is presumably caused by another polarization effect but spontaneous polarization, such as space charge. To investigate the origin of the dispersion of , n, discharging property was evaluated. When the signal at 1 kHz was applied, ZnO: 3 and 5 at% Mn showed the discharging with relaxation time of 5 msec. Furthermore, the discharging property with same relaxation time was observed at 20 kHz at where the dispersion of , n was not observed. However, ZnO: 4 at% Mn does not show such a discharging behavior. Therefore, it is considered that the space charge is not the origin of the dispersion of , n. On the other hand, the dispersion of , n was minimum and no dielectric dispersion was observed at 20 kHz for all samples. The rc of ZnO: 3, 4 and 5 at% Mn measured at 20 kHz, which should be the rc originated from the spontaneous dipolar polarization, were derived to be 0.81, 0.81 and 0.62 pm/V, respectively. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of ZnO single crystals by an induced nucleation from a high temperature solution of the ZnO-PbF2 systemCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007Xinhua Li Abstract To grow ZnO single crystals from a high temperature solution of the ZnO-PbF2 system, a gas cooling system was assembled at the bottom of the crucible to induce nucleation in the initial growth stage. The growth experiments were carried out in a homemade vertical Bridgman furnace and Pt crucible of 28 mm in diameter was used. The furnace temperature was set to 1100°C and the flow rate of the oxygen gas was optimized as 3.0 l/min. ZnO crystal up to 5,8mm in the thickness was obtained with the lowering rate of 0.3 mm/h. XRD patterns showed that the as-grown crystal was pure ZnO Wurtzite phase. The impurity ions were analyzed by the glow discharge mass spectroscopy (GDMS) as 390.0 ppm and 40.0 ppm for Pb2+ and F - , respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence properties of ZnO single crystals with polar and non-polar facesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006H. Sasaki Abstract Photoluminescence (PL) was circumstantially measured for ZnO single crystals with polar and non-polar faces. PL spectra of ZnO single crystals depended on the sector and polarity of ZnO single crystals. Emissions due to excitons from c -plane substrates sliced from the +c sector were strong, and FWHMs of the emissions were smaller than those from substrates sliced from the ,c sector. An emission due to neutral-donor-bound exicitons (D0X) at 3.361 eV was dominantly observed on all surfaces of ZnO single crystals, and an emission due to ionized-donor-bound excitons (D+X) around 3.366 eV was observed on the O-face but not on the Zn-face at 4.2 K. It is thought that surface state densities due to oxygen caused this difference in PL emission for polarity of ZnO. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||