@article {11964,
	title = {The Influence of Nitrogen Ion Energy on the Quality of GaN Films Grown with Molecular Beam Epitaxy},
	journal = {Journal of Electronic Materials},
	volume = {24},
	number = {4},
	year = {1995},
	month = {04/1995},
	pages = {249-255},
	chapter = {249},
	abstract = {<p>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.</p>},
	keywords = {Activated nitrogen, GaN, molecular beam epitaxy (MBE), nitrogen ion energy},
	issn = {0361-5235},
	doi = {10.1007/BF02659683},
	author = {T.C. Fu and Nathan Newman and Erin C.  Jones and James S. Chan and Xiaohong Liu and Michael D. Rubin and Nathan W. Cheung and Eicke R. Weber}
}
@article {1900,
	title = {Thermal Annealing Characteristics of Si and Mg-implanted GaN Thin Films},
	journal = {Applied Physics Letters},
	volume = {68},
	number = {19},
	year = {1995},
	month = {03/1996},
	pages = {2702-2704},
	chapter = {2702},
	abstract = {<p>In this letter, we report the results of ion implantation of GaN using <sup>28</sup>Si and <sup>23</sup>Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 30 keV10^<sup>14</sup> cm<sup>-2</sup> Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690 {\textdegree}C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties.</p>},
	keywords = {annealing, crystal doping, defect states, electrical properties, gallium nitrides, ion implantation, magnesium additions, microstructure, silicon additions},
	issn = {0003-6951},
	doi = {10.1063/1.116314},
	author = {James S. Chan and Nathan W. Cheung and Lawrence F. Schloss and Erin C.  Jones and William S. Wong and Nathan Newman and Xiaohong Liu and Eicke R. Weber and A. Gassman and Michael D. Rubin}
}
