Gallium Nitride Thick Films Grown by Hydride Vapor Phase Epitaxy
- PDF / 1,940,065 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 102 Downloads / 267 Views
ABSTRACT Gallium nitride (GaN) thick films (to 150 ýtm) have been deposited by hydride vapor phase epitaxy (HVPE). These films are unintentionally doped n-type (n = 1-2 x 10I7 cm-3 at 300 K) and exhibit structural and electronic properties which are comparable with the best reported for GaN films grown by organometallic vapor phase epitaxy. Additionally, these properties are found to be uniform over 2-in diameter films grown on sapphire substrates. The use of either a GaCI or ZnO surface pretreatment has been found to substantially enhance the nucleation density, resulting in improved surface morphology and film properties, even though it appears that the ZnO film is thermochemically desorbed early on in the growth. Dislocation densities as low as -5x10 7 cm-' have been attained for films 40 ýtm thick. Homoepitaxial overgrowths both by electron-cyclotron-resonance plasma enhanced molecular beam epitaxy and OMVPE proceed in a straightforward manner, essentially replicating the defect structure of the HVPE GaN film.
INTRODUCTION The development of low-defect, controllably doped III-V nitride heterostructures has led to the realization of high power light emitting diodes (LED's) in the yellow to ultraviolet"3 and, more recently, injection laser diodes.4 However, a number of important issues preclude the CW operation of injection lasers and severely inhibit the economical commercialization of these devices. Specifically, epitaxial growth irreproducibility and film inhomogeneity inflict significant yield problems in LED production. In addition, current crowding effects are expected to be predominant in sapphire-substrate based injection lasers with underlying conductive layers
Data Loading...
