Behavior of Etching Process on Formation of Porous Polycrystalline GaN Layer through Electroless Etching

Abstract

At the first stage of this work, growth of polycrystalline GaN layer on GaAs (100) substrate using RF-sputtering was demonstrated at room temperature, with and without the insertion of AlN as a buffer layer. Diffraction pattern from XRD measurement of the samples showed the evidence of GaN in and (0002) orientations. It was found that the FWHM of the GaN for both samples, with and without the AlN buffer layer were 0.17°. However, the FWHM of the GaN (0002) peak for the sample with the AlN buffer layer was 0.08°, while without the AlN buffer layer was 0.16°. Next, both samples were fabricated into porous structure through electroless etching for 3 and 5 minutes, respectively. The cubic inverse truncated pyramid-like porous structure was observed. Detailed inspection found that the etching rate reduced as the etching time increased. More interestingly, the 3 minutes etched-porous on the GaN sample without the AlN buffer layer showed better porosity compared to its counterparts. It is proposed that low properties of GaN sample tends to have high etching rate and better porosity profile in term of pores distribution and density and this is due to weak Ga-N bonding.