%0 Journal Article %J Journal of Electronic Materials %D 1995 %T The Influence of Nitrogen Ion Energy on the Quality of GaN Films Grown with Molecular Beam Epitaxy %A T.C. Fu %A Nathan Newman %A Erin C. Jones %A James S. Chan %A Xiaohong Liu %A Michael D. Rubin %A Nathan W. Cheung %A Eicke R. Weber %K Activated nitrogen %K GaN %K molecular beam epitaxy (MBE) %K nitrogen ion energy %X

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.

%B Journal of Electronic Materials %V 24 %P 249-255 %8 04/1995 %G eng %N 4 %1

Windows and Daylighting Group

%2 LBL-37223 %& 249 %R 10.1007/BF02659683 %0 Conference Paper %D 1994 %T Fundamental Materials-Issues Involved in the Growth of GaN by Molecular Beam Epitaxy %A Nathan Newman %A T.C. Fu %A Z. Liu %A Zuzanna Liliental-Weber %A Michael D. Rubin %A James S. Chan %A Erin C. Jones %A Jennifer T. Ross %A Ian M. Tidswell %A Kin Man Yu %A Nathan W. Cheung %A Eicke R. Weber %X

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.

%G eng %L LBL-37296 %2 LBL-37296 %0 Conference Paper %B Materials Research Society %D 1993 %T Comparison of AIN Films Grown by RF at Magnetron Sputtering and Ion-Assisted Molecular Beam Epitaxy %A James S. Chan %A T.C. Fu %A Nathan W. Cheung %A Jennifer T. Ross %A Nathan Newman %A Michael D. Rubin %X

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.

%B Materials Research Society %C San Francisco, CA %V 300 %8 04/1993 %G eng %1

Windows and Daylighting Group

%2 LBL-35660 %0 Journal Article %J Applied Physics Letters %D 1993 %T P-Type Gallium Nitride by Reactive Ion-Beam Molecular Beam Epitaxy with Ion Implantation, Diffusion or Coevaporation of Mg %A Michael D. Rubin %A Nathan Newman %A James S. Chan %A T.C. Fu %A Jennifer T. Ross %K carrier density %K carrier mobility %K crystal doping %K diffusion %K evaporation %K gallium nitrides %K ion implantation %K magnesium additions %K molecular beam epitaxy %K p−type conductors %X

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.

%B Applied Physics Letters %V 64 %P 64-66 %G eng %N 1 %1

Windows and Daylighting Group

%2 LBL-34413 %! Appl. Phys. Lett. %& 64 %R 10.1063/1.110870