The Preparation And Characterizations Of Nanoporous GaN Films

Gallium Nitride (GaN) is a large energy gap and direact band gap semiconductor materials(energy gap is3.4eV,exciton binding energy is21meV),by the excellent properties of high carrier concentration, high electronic mobility(to900cm2/(V·s) at room temperature), Chemical stability(insoluble in water,acid and alkali), adamantine,high melting point(about1700℃), low dielectric constant, Strong atomic bonds and high breakdown electric field,so it can be used in ultraviolet detector, high brightness LED, blue light laser and high frequency, high pressure, high temperature, radioresistance,high power devices.Ecthing technology,one of the microelectro technology,is that selective corrosion and sripping the semiconductor substrate and surface coverd films methods according to the mask pattern or design requirements. However,because of the chemical stability of GaN,it’s difficult for etching of the GaN films.After years of effort,we have achived the etching of the GaN films by many methods,such as metal-assisted chemical etching, light-assisted electrochemistry and electrichemistry and so on.In this paper,we focus on the nanoporous GaN films,reaserched the mechanism of the electrochemical etching, characrteristic of the promoted properties by nanoporous structure,annealed the nanoporous GaN films and as the nanoporous GaN for buffer to epitaxy growth the Ga2O3films.Firstly,we studed the influence of ultravoiolet and durations on the etching,and based on this studing,we get the self-standing nanoporous GaN films.Secondly, we characrteristic the properties of nanoporous GaN films by different etching conditions and self-standing nanoporous GaN films, qualitative analysis and quantitative calculation the change of materials’stress with different porousities and photo luminescence.Thirdly,we annealed the nanoporous GaN films in O2conditons,prepared the nanocavities,as the processing of the annealed,the nanocavities produced and changed. In addition,we find nanotips also,by change the temperature or durations of etching, we can charge the height and density and substrate of the nanotips(when the annealed tempetature is800℃,the substrate of the nanotips is GaN and when900℃the substrate of the nanotips is heterostructure of GaN/Ga2O3).Lastly,because of the relaxation of the compressive and increasing of the elasticity modulus,we take the nanoporous GaN films as buffer to epitaxy growth the Ga2O3films by metal organic chemical vapor deposition(MOCVD), prepard the hetero structure of GaN/Ga2O3with smooth interface by epitaxy growthing.