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Quantum and transport scattering times related to different subbands in modulation-doped Al0.22Ga0.78N/GaN single quantum wells (SQW) have been studied by magneto- transport measurements. The quantum scattering time related to the first and the second subbands is determined to he 0.078 ps and 0.088 ps, respectively, at 1.5 K. Results indicate that the scatterings from heterointerface and ionized donors at both side of GaN well are all important in limiting quantum scattering time. By using mobility spectrum technique the transport scattering time related to the first subband is determined to he 0.128 ps. Transport-to-quantum scattering time ratio in the first subband is 1.6. It is concluded the large angle scatterings play a very important role in limiting quantum scattering time in this SQW. [ABSTRACT FROM AUTHOR]

ZnO films were prepared on (0002) sapphire by metal-organic chemical vapor deposition (MOCVD) with fixed Zn and O gas flow rates. The film properties displayed complex dependencies on temperature over the range 330–460 °C. All films were preferentially oriented along the (0002) direction and the integrated intensity of the (0002) peak increased with increasing substrate temperature, indicative of an increasing deposition rate. Furthermore, high substrate temperatures promoted the growth of columnar grains, and improved the crystallinity, as the decreasing FWHM of the (0002) ZnO peak suggests. However, it was not the highest temperature sample, but the sample deposited at 390 °C that had the best UV band emission characteristics, with no defect-related luminescence in the photoluminescence (PL) spectra, as well as the highest transmission and sharpest absorption edge in the transmittance spectra. [ABSTRACT FROM AUTHOR]

Abstract. Thin heteroepitaxial films of Si[sub 1-x-y]Ge[sub x]C[sub y] have been grown on Si(100) substrates by rapid thermal chemical vapor deposition (RTCVD) using C[sub 2]H[sub 4] as C source. The composition and microstructure of Si[sub 1-x-y]Ge[sub x]C[sub y] films were characterized by Auger electron spectroscopy, Raman spectra and Fourier-transform infrared spectroscopy. The results show that lower temperature and higher SiH[sub 4]/C[sub 2]H[sub 4] flow ratio are helpful in forming the substitutional C and improving the crystal quality. A possible mechanism for C incorporation in Si[sub 1-x-y]Ge[sub x]C[sub y] layers grown by RTCVD using C[sub 2]H[sub 4] is proposed. [ABSTRACT FROM AUTHOR]

Abstract. The transient photoconductivity (PC) properties of GaN thin film on (0001) sapphire substrate are investigated. The decay curves of PC obtained by YAG:Nd pulsed laser are divided into two special regions, which are the beginning and tail decay regions, corresponding to two time constants, 0.1 ms and 1.0 ms, respectively. Keeping the same light intensity and bias voltage, when the sample is heated to 300 Celsius, the time constants are both reduced. It shows that there are a large number of traps at the position of tens of meV below the conduction band edge. The PC ascends S-shaped when the data are collected during the first 200 ns. As the sample is not illuminated, the PC sharply reduces and oscillates, indicating that the carriers redistribute between the deep traps and the conduction band. As an approximation, a model involving two trapping levels, the shallow and the deep trapping levels represents the structure of the electron trapping levels in the gap. The simulation based on this model is well in accordance with the experimental results. Moreover, the mechanism of how the PC curves varied as the light intensity is explained by the model. [ABSTRACT FROM AUTHOR]

Abstract: The effect of alloying and expitaxial mismatch strain on the surface ultraviolet (UV) emission efficiencies of AlxGa1−xN films, pseudomorphically grown on both c- and m-plane AlyGa1−yN templates (x−0.03+1.79x−0.06x2 (0

Abstract: Impact of anisotropic strains on low-frequency dielectric properties and room-temperature polar phases of SrTiO3 epitaxial thin films is investigated. The dielectric properties show a remarkable change as a function of anisotropic strains. The number of room-temperature polar phases is as twice as that of isotropically strained SrTiO3 thin films. [Copyright &y& Elsevier]

Abstract: Structural and optical properties of a-SiN x films deposited by electron cyclotron resonance chemical vapor deposition (ECRCVD) have been investigated. The Fourier transform infrared (FTIR) spectroscopy shows the structural evolution of the SiN x films, which are defined as Si-rich SiN x and N-rich SiN x films, also confirmed by Raman spectroscopy. The origin of the light emission for SiN x films may be attributed to two mechanisms, i.e., quantum confinement effect (QCE) and transition of defect energy levels. The correlation between light emission and structures of SiN x films is discussed. [Copyright &y& Elsevier]

Abstract: The LiNbO 3 thin films are successfully grown by pulsed-laser deposition on theAl 0.28 Ga 0.72 N/GaN substrate. The films are characterized by the X-ray diffraction and the X-ray photoelectron spectroscopy. The ferroelectric properties are measured by the piezoresponse force microscopy. An Al/SiO 2 /LiNbO 3 /Al 0.28 Ga 0.72 N/GaN structure is then fabricated and measured by high frequency capacitance–voltage at 1MHz. The mechanism of interaction between interfaces is revealed. [Copyright &y& Elsevier]