Characterization Of Etch Pit Density For Gallium Nitride Layer Grown By Hvpe And Mocvd

We investigated the characterization of dislocations for GaN epilayers grown by HVPE and MOCVD methods through wet-chemical etching method, cathodoluminescence (CL) and high resolution X-ray diffraction (HR-XRD). The thickness of GaN epilayers grown by HVPE and MOCVD was prepared 15 mu m and 5 mu m, respectively. To evaluate etch pits density (EPD) of GaN epilayers by wet-chemical etching, samples were etched in molten KOH at 400 degrees C. The EPD for GaN grown by HVPE and by MOCVD was measured in close agreement with the respective dislocation density obtained by CL and HR-XRD. In case of GaN grown by HVPE, dislocation densities were 6.9x10(7)/cm(2) by EPD, 6.5x10(7)/cm(2) by CL, and 2.9x10(7)/cm(2) by HR-XRD. For GaN grown by MOCVD, dislocation density was 4.7x10(8)/cm(2) by EPD, 5.8x10(8)/cm(2) by CL, and 1.4x10(8)/cm(2) by HR-XRD. For GaN grown by MOCVD on patterned sapphire substrate, dislocation density was 1.0x10(8)/cm(2) by EPD, 2.2x10(8)/cm(2) by CL and 7.2x10(7)/cm(2) by HR-XRD. Dislocation density of GaN grown by HVPE showed the lower value among these samples. Also we could expect that the wet-etching method at proper etching condition and time might be accurate determination method to investigate the dislocations in GaN epilayers. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim