@article{more_ailey_lowden_lin_1999, title={Evaluating the effect of oxygen content in BN interfacial coatings on the stability of SiC/BN/SiC composites}, DOI={10.1016/S1359-835X(98)00135-3}, abstractNote={Boron nitride was studied as a fiber–matrix interface coating for Nicalon™/SiC composites. The effect of initial O-impurity content within the as-processed BN coatings on the long-term interface stability was investigated at elevated temperatures in flowing oxygen. Two types of Nicalon™/SiC composites were used for this study; one composite had a BN coating with <2% oxygen (low-O BN) and another composite had BN with an oxygen concentration >11% (high-O BN) in the as-processed state. The high-O BN is actually most representative of BN coatings available commercially. The BN coatings in both the high-O and low-O BN containing composites were structurally similar. The samples used here were thinned to <200 μm before oxidation and the final preparation for electron microscopy examination of the interface region was done after the reactions were completed. Thin samples were used to simulate maximum corrosion effects that would occur at the surface of an actual part during service. Ech sample was exposed to flowing oxygen at temperatures as high as 950°C for times up to 400 h. After each oxidation experiment, the BN coatings were examined by TEM to quantify the extent of any reaction which occurred at either the fiber/BN and BN/SiC matrix interfaces. At 950°C for 100 h, there were no interface microstructural changes observed in the low-O BN but there was extensive silica formation at the fiber/BN interfaces in the high-O BN. After 400 h at 950°C, large voids formed at the fiber/BN interface in the high-O BN sample only. Oxygen present within the initial BN coating contributed significantly to the degradation of the interfacial properties of the composite. Several techniques, including transmission electron microscopy (TEM), Auger electron spectroscopy (AES), energy-dispersive spectrometry (EDS), and electron energy-loss spectroscopy (EELS) were used to characterize changes in structure and chemistry of the fiber–matrix interface region and to elucidate and quantify composite degradation mechanisms.}, number={4}, journal={Composites Part A Applied Science and Manufacturing}, author={More, K.L. and Ailey, K.S. and Lowden, R.A. and Lin, H.T.}, year={1999}, month={Apr} }
 @article{davis_paisley_sitar_kester_ailey_linthicum_rowland_tanaka_kern_1997, title={Gas-source molecular beam epitaxy of III–V nitrides}, DOI={10.1016/S0022-0248(97)00077-8}, abstractNote={Abstract Amorphous, hexagonal and cubic phases of BN were grown via ion beam assisted deposition on Si(1 0 0) substrates. Gas-source molecular beam epitaxy of the III–V nitrides is reviewed. Sapphire(0 0 0 1) is the most commonly employed substrate with 6H-SiC(0 0 0 1), ZnO(1 1 1) and Si(1 1 1) also being used primarily for the growth of wurtzite GaN(0 0 0 1) in tandem with previously deposited GaN(0 0 0 1) or AlN(0 0 0 1) buffer layers. Silicon(0 0 1), GaAs(0 0 1), GaP(0 0 1) and 3C-SiC(0 0 1) have been employed for growth of cubic (zincblende) β-GaN(0 0 1). The precursor materials are evaporated metals and reactive N species produced either via ECR or RF plasma decomposition of N2 or from ammonia. However, point defect damage from the plasma-derived species has resulted in a steady increase in the number of investigators now using ammonia. The growth temperatures for wurtzite GaN have increased from 650 ± 50°C to 800 ± 50°C to enhance the surface mobility of the reactants and, in turn, the efficiency of decomposition of ammonia and the microstructure and the growth rate of the films. Doping has been achieved primarily with Si (donor) and Mg (acceptor); the latter has been activated without post-growth annealing. Simple heterostructures, a p-n junction LED and a modulation-doped field-effect transistor have been achieved using GSMBE-grown material.}, number={1/2}, journal={Journal of Crystal Growth}, author={Davis, R.F. and Paisley, M.J. and Sitar, Z. and Kester, D.J. and Ailey, K.S. and Linthicum, K. and Rowland, L.B. and Tanaka, S. and Kern, R.S.}, year={1997}, month={Jun} }
 @article{davis_weeks_bremser_tanaka_kern_sitar_ailey_perry_wang_1997, title={Growth of AlN and GaN thin films via OMVPE and gas source MBE and their characterization}, DOI={10.1016/S0038-1101(96)00152-9}, abstractNote={Thin films of AlN and GaN are deposited primarily via the common forms of organometallic vapor phase epitaxy (OMVPE) and molecular beam epitaxy (MBE). Sapphire is the most common substrate; however, a host of materials have been used with varying degrees of success. Both growth techniques have been employed by the authors to grow AlN and GaN primarily on 6H-SiC(0001). The mismatch in atomic layer stacking sequences along the growth direction produces inversion domain boundaries in the AlN at the SiC steps; this sequence problem may discourage the nucleation of GaN. Films of AlN and GaN grown by MBE at 650°C are textured; monocrystalline films are achieved at 1050°C by this technique and OMVPE. Donor and acceptor doping of GaN has been achieved via MBE without post growth annealing. Acceptor doping in CVD material requires annealing to displace the H from the Mg and eventually remove it from the material. High brightness light emitting diodes are commercially available; however, numerous concerns regarding metal and nitrogen sources, heteroepitaxial nucleation, the role of buffer layers, surface migration rates as a function of temperature, substantial defect densities and their effect on film and device properties, ohmic and rectifying contacts, wet and dry etching and suitable gate and field insulators must and are being addressed.}, number={2}, journal={Solid-State Electronics}, author={Davis, Robert F. and Weeks, T.W. and Bremser, M.D. and Tanaka, S. and Kern, R.S. and Sitar, Z. and Ailey, K.S. and Perry, W.G. and Wang, C.}, year={1997}, month={Feb} }
 @article{davis_bremser_perry_ailey_1997, title={Growth of AlN, GaN and AlxGa1 − xN thin films on vicinal and on-axis 6HSiC(0001) substrates}, DOI={10.1016/S0955-2219(97)00077-0}, abstractNote={Monocrystalline GaN(0001) thin films were grown at 950 °Con AlN(0001) buffer layers previously deposited at 1100 °C on α(6H)-SiC(0001)si substrates via metallorganic chemical vapor deposition (MOCVD). Films of AlxGa1 − xN (0 ≤ x ≤ 1) were grown directly on the same SiC surface at 1100 °C. X-ray rocking curves for the GaN(0004) reflection for 1.4 μm films revealed FWHM values of 58 and 151 arc sec for materials grown on on-axis and offaxis substrates, respectively. Cathodoluminescence exhibited strong near band-edge emission for all materials. Controlled n- type Si-doping in GaN and AlxGa1 − xN (for x ≤ 0.4) was achieved with net carrier concentrations ranging from approximately 2 × 1017 cm− 3 to 2 × 1019 (AlxGa1 − xN) or to 1 × 1020 (GaN) cm− 3. Mg-doped, p-type GaN and AlxGa1 − xN (for x ≤ 0.13) was achieved with nA − nD ≈ 3 × 1017 cm− 3.}, number={15-16}, journal={Journal of the European Ceramic Society}, author={Davis, Robert F. and Bremser, M.D. and Perry, W.G. and Ailey, K.S.}, year={1997}, month={Jan} }