Current Confinement Effect of InGaN Devices by Forming Photoelectrochemical-Oxidized GaN Nanoporous Structures

Wednesday, May 14, 2014: 10:35
Manatee, Ground Level (Hilton Orlando Bonnet Creek)
C. F. Lin (National Chung Hsing University, Yale University), W. C. Lee, Y. L. Chen, Y. H. Tseng, J. J. Dai (National Chung Hsing University), and J. Han (Yale University)
Aperture of InGaN light emitting diode (LED) structure was demonstrated by forming oxidized GaN nanoporous structure bellow the InGaN active layer. The fabricated processes consisted of a laser drilling hole process, a photoelectrochemical (PEC) lateral etching process, and a oxidation process. The LED structures consisted of a 30nm-thick GaN buffer layer, a 2μm-thick undoped GaN layer, a 2μm-thick n-type GaN layer, 0.7μm-thick current blocking layers, 10 pairs of the InGaN/GaN multiple quantum wells (MQWs) active layers, and a 0.2μm-thick magnesium-doped p-type GaN layer. 0.1μm u-GaN/0.5μm n-GaN:Si/0.1μm u-GaN layers were designed as current blocking layers for PEC processes. The current block layer The active layers consisted of a 30Å-thick InGaN-well layer and a 70Å-thick GaN-barrier layer. High resistance oxidized GaN nanoporous structure was formed embedded the LED structure that the injection current can confine in an aperture region. The aperture regions of the InGaN devices were observed clearly in optical and scanning electron microscopy (SEM) images. The peak photoluminescence (PL) spectra of the InGaN active layers were measured at 439.5nm and 435.6nm without and with embedded oxidized GaN nanoporous structure, respectively. The oxidized GaN nanoporous structure acted a current confinement structure that has potential for vertical cavity surface emitting laser applications.