Growth And Characteristics Of In-Doped Gan Thin Films

In-doped GaN thin films were grown by metalorganic chemical vapor deposition (MOCVD) with different trimethylindium (TMIn) flow rates and those structural and electrical characteristics were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), Hall effect measurement and deep level transient spectroscopy (DLTS). The full width at half maximum (FWHM) of X-ray rocking curves and the pit density, which is estimated by AFM images, decrease with increasing TMIn flow rate. It seems that In doping has definite effects of reducing dislocation density in In-doped GaN films. Hall mobility increases with increasing TMIn flow rate. As an explanation, from an analysis of temperature-dependent Hall effect measurements based on a two-layer mixed conduction model, the mobility contribution of the epilayer compared to that of the interface layer between GaN and sapphire is increased due to reduction of dislocation density in In-doped GaN thin films. It is also observed that the reduction of deep level E2 is related to In-doping.