Structural Properties of Doped GaN on Si(111) Studied by X-Ray Diffraction Techniques

X-ray diffraction (XRD) is a non-destructive technique which is widely used in material characterization, particularly to determine structure, crystalline quality and orientation of samples. Two representative samples are used in this work, these samples are sample I (Si-doped GaN/AlN/Si) nominally consisted of 284 nm AlN followed by 152 nm of Si-doped GaN, and sample II (Mg-doped GaN/AlN/Si), grown with 194 nm AlN followed by 136 nm of Mg-doped GaN. Both doped GaN films were investigated by high resolution X-ray diffraction (HRXRD) with rocking curve (RC) measurement around the symmetrical (0002) and asymmetrical (10 (1) over bar2) diffraction peaks. The phase analysis result revealed that monocrystalline GaN was obtained. The XRD pattern show sharp and well separated (0001) reflections of doped GaN and AlN indicating complete texture with GaN[0 0 0 2] parallel to AlN[ 0 0 0 2] parallel to Si[1 1 1]. From the HRXRD RC omega/2 theta scans of (1012) and (0002) plane, we determined both a and c lattice parameters of the doped GaN. The symmetrical and asymmetrical RC full width at half maximum (FWHM) of doped GaN were obtained.