Lumineszenzeigenschaften von pyrolytisch abgeschiedenem GaN

Abstract

The pyrolytic deposition process of Gah-011 insulating substratc inaterials results i n metallic black to marly colourless layers. Morphology arid groivth rates are infliienced by growth terriperaturc, nature and flow ratcs of the carrier gases. In the cathotloliirniriescericc characteristic emission bands w w e foniid from E ( P ) = 3.54 to 3.10 eV end E ( P ) = 2.21 t o 2.07 rV, the relative intensities of which depend on tho flow rate of tlie used carrier gas. Yellow arid colourless layers exhibit, partly alone, a peak at E ( P ) = 2.48 el'. The external quantum yield reaches a maximum for da.rk, inetallic layers. Het'wccri the growt,h parainetnrs and tho concentration of vacancies and incorporation of impurities also, a coiinection exists in a manricr shown by the spectra. Die pyrolytische Abscheidung vori GaN auf isolierenden S~ibstratinnterialien fuhrt z u inctallisch schwarzen bis riahczu farblosen Schichten. Morphologie iind Wachstumsrate xverdcii becinflul3t durch Waehstnmsternperatur sowie Art und Stromungsraten des Triigergases. I m Katodolurnineszenzspektrum w x d e r i charaktrristische Ernissionsbandeii in der Nuhe der Baridkarite h i 3,54...3,10 eV sowie bci 2,21..-2,07 eV erhalt'en, deren relative Interisitiitcn vori der Stromnngsrate des Triigcrgasstromcs abhiirigen. Rci gelber uiid iarhloser Probe erscheint, z. T. ausschlieBlich, ein Peak bei 2.48 eV. Dic iiiul3ereQiiantoiiausbentc ist fur dunklc, metallische Proben a m grol3ten. Zbvischen den Zuchtungsparameterri iind der Vakanzeiiko~izentration sowie dem Verurireinigungseiiibau (Sauerstoff) bosteht ein durch die Spektreri ausgewiesener Zusammenliang.

DFT Modeling of Chemical Vapor Deposition of GaN from Organogallium Precursors. 1. Thermodynamics of Elimination Reactions

“…Many different chemical vapor deposition (CVD) processes have been employed to produce high purity monocrystalline GaN, and a variety of precursors, such as azides, hydrazides, and different types of donor−acceptor adducts have been proposed and examined. − One of the commercially most important ways to synthesize GaN is via the metal organic vapor phase epitaxy (MOVPE) of trimethylgallium Ga(CH 3 ) 3 (TMG) and ammonia. Petzke and Zehe found that under atmospheric pressure the Ga(CH 3 ) 3 (g) + NH 3 (g) = GaN(s) + 3CH 4 (g) equilibrium is almost quantitatively moved to the right side at T > 800 °C. The thermodynamic analysis of this reaction has been presented by Chegnov et al One of the major factors affecting the GaN deposition is the donor−acceptor interaction of the TMG and NH 3 components and their adduct formation …”