Papers by Keyword: Carrier Concentration

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Authors: Hiroaki Saitoh, Tsunenobu Kimoto
Abstract: Chemical vapor deposition of 4H-SiC on (0001) substrates with various off-angles from 1o to 45o has been investigated. On large-off-angled (15o-45o) substrates, very smooth surface morphology is obtained in the wide range of C/Si ratio. The micropipe dissociation during epitaxial growth is observed on 4o-45o off-angled substrates with a low C/Si ratio. The incorporation of nitrogen was dramatically suppressed by increasing C/Si ratio irrespective of substrate’s off-angle.
Authors: K. Narita, Yasuto Hijikata, Hiroyuki Yaguchi, Sadafumi Yoshida, Junji Senzaki, Shinichi Nakashima
Authors: N. Wieser, M. Klose, F. Scholz, J. Off, Y. Dutrieux
Authors: Peter P. Murmu, John Kennedy, Ben J. Ruck, Andreas Markwitz
Abstract: We report the structural and electrical properties of ion beam sputtered ZnO films vacuum annealed at varying temperatures. XRD results revealed that the films grow along the c-axis. The crystallite sizes increase from ~8 to ~30 nm upon annealing at 800 ºC. Annealing aided to recover the compressive strain and regain the standard lattice parameter values. The RMS surface roughness increased to ~5.0 nm after annealing at 800 ºC as observed in AFM micrographs. Increased resistivity on the annealed films suggested that the oxygen vacancies are compensated by de-trapped oxygen at grain boundaries.
Authors: N.C. Halder, J. Martin, D. Sisler Jr.
Abstract: We have investigated deep trap concentrations in hydride vapor pressure epitaxy (HVPE) - grown GaN by measuring three-dimensional carrier concentration profiles and ionization energies. Schottky contacts were fabricated on 28-68μm thick films using Ni/Au contacts. Extensive capacitance-voltage measurements were made in the temperature range 100-350K at reverse bias voltages in the range 0 to –5V. Effective carrier concentrations and ionization energies were determined from three-dimensional plots of concentration-temperature-depth. Carrier concentration versus temperature plots show slowly changing three-step behavior. During the first step, all the plots rise linearly up to about 200K reaching respective plateaus before reversing courses downwards again linearly. Ionization energy plots, on the other hand, are almost linear all the way up to 350 K showing some tendency of upward bending. Trap concentrations were determined from carrier concentrations and previously measured deep level transient spectroscopy (DLTS) plots as function of reverse bias voltages. In almost every case, trap concentrations also rise linearly with increasing depth in the samples.
Authors: Li Hong Cheng, L. Yu, F. Yu, Z.Z. Lu, Xiang Fu Zhao, Ping Han, H. Zhao, Z.L. Xie, X.Q. Xiu, R. Zhang, Y.D. Zheng
Abstract: The Ge mole fraction (x) of Si1-xGex layer was described by the C-V technique for Schottkey contact of single heterojunction Si1-xGex/Si, whose structure profile can be characterized by SEM image and EDS. Then the strained Si cap layer was grown on the Si1-xGex/Si, and C-V technique was used to determine the carrier concentration and structure of double heterojunction Si/Si1-xGex/Si. The change of the structure between Si1-xGex/Si and Si/ Si1-xGex/Si was also observed by this method.
Authors: M. Asghar, Khalid Mahmood, M.A. Hasan
Abstract: We have grown a plenty of samples to investigate the effect of substrate temperature on the structural and electrical properties of grown films. X-ray diffraction analysis confirmed the hexagonal structure of ZnO with preferred c-orientation. As we increased the substrate temperature from 74 °C to 500 °C, the microstructure of films improved. The position of (002) peak remained constant but its intensity increased remarkably with increasing substrate temperature. The FWHM of films decreased and crystalline size increased with substrate temperature. We also observed strong dependence of electrical properties on the substrate temperature. The thickness, resistivity and growth rate are directly proportional to the substrate temperature. The possible reason of higher resistivity of thick films is that with improved microstructure, ZnO films have low density of interstitials defects, which acted as free carriers and therefore results in the increased of resistivity.
Authors: Liu Di Jiang, Le Zhong, Fred Reed, Salim Taysir, Matteo Bosi, Giovanni Attolini
Abstract: 3C-SiC have been epitaxially grown through vapour phase expitaxy under a different grow conditions. Key electrical properties of these SiC layers have been characterised by fabrication and measurement of metal-SiC-metal devices. The electrical properties of SiC grown at different conditions have been analysed based on their structural and crystalline quality.
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