Controlled porosity of GaN using different pore size of Si (100) substrates

This work demonstrated the ability of controlling porosity of GaN using different pore size of Si (100) substrates. Initially, the porous Si substrates were prepared by electrochemical etching using different time of etching; 10 min, 20 min and 30 min. The surface morphology of the substrates indicated that the pores size increased by increasing the time of etching. Next, GaN layer was grown directly onto the porous Si substrates using RF-sputtering. It was found that a thin GaN layer was grown on the 10 min-etched porous Si substrate with some tiny pores on the surface. On the other hand, the 30 min-etched porous Si substrate led to the formation of porous GaN. Estimated threading dislocation density from the XRD measurement showed that the porous Si substrate helped to improve the crystalline properties of the GaN layer. Meanwhile, the porous GaN has much better properties than other previously reported porous GaN. (C) 2014 Elsevier Ltd. All rights reserved.