Current blocking effect of GaN nanoporous structures

• Main Authors: Jing-Hao Wang, 王鏡皓
• Other Authors: 林佳鋒
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/mr5f5x

碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === In this paper, an InGaN-based LED structure was treated by Focused Ion Beam (FIB) and formed nanoporous n-GaN structure by EC wet etching process in oxalic acid solution. Through the FIB, the beauty particular micro-pattern could be formed, and then utilizing the selectively etching between n-GaN and other structure layer in oxalic acid solution, the nanoporous structure was only formed in n-GaN layer by EC wet etching process. The characteristics of the nanoporous structure LED were analyzed in detail into two parts. In the first part, we used FIB to drill holes and form the rod-bridge (RB) pattern at the center of the devices (RB-LED), After the sample was immersed into the oxalic acid solution with an external DC bias fixed at 15 V for 2 min, the n-GaN layers were etched and formed porous structure through EC wet etching process (ECRB-LED). The light output power of the sidewall had approximate 77.27% enhancement when compared to the ST region at 2mA. And the wavelength blushift of RB region was less than ST region because of the stress relaxation. Additionally, the external current was blocked by nanoporous structures. This phenomenon was called current blocking effect. In the second part, we used FIB to drill four patterns with different residual width (4, 6, 8, and 10μm) at the center of four different devices. After the sample was immersed into the oxalic acid solution with an external DC bias fixed at 15 V for 2 min, the n-GaN layers were etched and formed porous structure through EC wet etching process. The light-intensity profiles of the four devices were observed at 0.07mA. The limit width was 8μm which would cause the current blocking effect. And the influence of the current blocking effect was increased when the residual width was decreased.