TY - JOUR T1 - The Influence of Nitrogen Ion Energy on the Quality of GaN Films Grown with Molecular Beam Epitaxy JF - Journal of Electronic Materials Y1 - 1995/04// SP - 249 EP - 255 A1 - T.C. Fu A1 - Nathan Newman A1 - Erin C. Jones A1 - James S. Chan A1 - Xiaohong Liu A1 - Michael D. Rubin A1 - Nathan W. Cheung A1 - Eicke R. Weber KW - Activated nitrogen KW - GaN KW - molecular beam epitaxy (MBE) KW - nitrogen ion energy AB - Since the growth of GaN using molecular beam epitaxy (MBE) occurs under metastable growth conditions, activated nitrogen is required to drive the forward synthesis reaction. In the process of exciting the nitrogen using a plasma or ion-beam source, species with large kinetic energies are generated. Impingement on the growth surface by these species can result in subsurface damage to the growing film, as well as an enhancement of the reverse decomposition reaction rate. In this study, we investigate the effect of the kinetic energy of the impinging nitrogen ions during growth on the resulting optical and structural properties of GaN films. Strong band-edge photoluminescence and cathodoluminescence are found when a kinetic energy of ~10 eV are used, while luminescence is not detectable when the kinetic energies exceeds 18 eV. Also, we find that the use of conductive SiC substrates results in more homogeneous luminescence than the use of insulating sapphire substrates. This is attributed to sample surface charging in the case of sapphire substrates and subsequent variation in the incident ion flux and kinetic energy across the growth surface.This study clearly shows that the quality of GaN films grown by MBE are presently limited by damage from the impingement of high energy species on the growth surface. VL - 24 IS - 4 U1 -

Windows and Daylighting Group

U2 - LBL-37223 DO - 10.1007/BF02659683 ER - TY - CONF T1 - Fundamental Materials-Issues Involved in the Growth of GaN by Molecular Beam Epitaxy Y1 - 1994/ A1 - Nathan Newman A1 - T.C. Fu A1 - Z. Liu A1 - Zuzanna Liliental-Weber A1 - Michael D. Rubin A1 - James S. Chan A1 - Erin C. Jones A1 - Jennifer T. Ross A1 - Ian M. Tidswell A1 - Kin Man Yu A1 - Nathan W. Cheung A1 - Eicke R. Weber AB - Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. Both Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) have recently made strong progress in fabricating high-quality epitaxial GaN thin films. In this paper, we review materials-related issues involved in MBE growth. We show that a strong understanding of the unique meta-stable growth process allows us to correctly predict the optimum conditions for epitaxial GaN growth. The resulting structural, electronic and optical properties of the GaN films are described in detail. U2 - LBL-37296 ER - TY - CONF T1 - Comparison of AIN Films Grown by RF at Magnetron Sputtering and Ion-Assisted Molecular Beam Epitaxy T2 - Materials Research Society Y1 - 1993/04// A1 - James S. Chan A1 - T.C. Fu A1 - Nathan W. Cheung A1 - Jennifer T. Ross A1 - Nathan Newman A1 - Michael D. Rubin AB - Crystalline aluminum nitride (AlN) thin films were formed on various substrates by using RF magnetron sputtering of an A1 target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AlN/(111) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 °C, while the crystallinity of AlN/(0001) Al2O3 samples improved from 700 to 850 °C. The optical absorption characteristics of the AlN/(0001) Al2O3 films as grown by both deposition methods revealed a decrease in sub-band gap absorption with increased substrate temperature. JF - Materials Research Society CY - San Francisco, CA VL - 300 U1 -

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U2 - LBL-35660 ER - TY - JOUR T1 - P-Type Gallium Nitride by Reactive Ion-Beam Molecular Beam Epitaxy with Ion Implantation, Diffusion or Coevaporation of Mg JF - Applied Physics Letters Y1 - 1993/ SP - 64 EP - 66 A1 - Michael D. Rubin A1 - Nathan Newman A1 - James S. Chan A1 - T.C. Fu A1 - Jennifer T. Ross KW - carrier density KW - carrier mobility KW - crystal doping KW - diffusion KW - evaporation KW - gallium nitrides KW - ion implantation KW - magnesium additions KW - molecular beam epitaxy KW - p−type conductors AB - Gallium nitride is one of the most promising materials for ultraviolet and blue light‐emitting diodes and lasers. The principal technical problem that limits device applications has been achieving controllable p‐type doping. Molecular beam epitaxy assisted by a nitrogen ion beam produced p‐type GaN when doped via ion implantation, diffusion, or coevaporation of Mg. Nearly intrinsic p‐type material was also produced without intentional doping, exhibiting hole carrier concentrations of 5×1011 cm−3 and hole mobilities of over 400 cm2/V/s at 250 K. This value for the hole mobility is an order of magnitude greater than previously reported. VL - 64 IS - 1 U1 -

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U2 - LBL-34413 JO - Appl. Phys. Lett. DO - 10.1063/1.110870 ER -