Optical and Electrical Properties of GaN-based Nanoporous Structures

• Main Authors: Cheng-Chian Chang, 張政謙
• Other Authors: Chia-Feng Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/34693841463603911495

碩士 === 國立中興大學 === 材料工程學系所 === 95 === In this thesis, the nanoporous p-type GaN:Mg structures were fabricated through a photoelectrochemical (PEC) oxidation and an oxide-removing process. The photoluminescence (PL) intensities of GaN and InGaN/GaN multi-quantum-well (MQW) structures were enhanced by forming this nanoporous structure to increase light extraction efficiency. The PL emission peaks of MQW active layer have the blueshift phenomenon from 461.8 nm (standard) to 456.3 nm (nanoporous) measured at 10 K caused by partially releasing the compressive strain from the top nanoporous GaN:Mg layers. The internal quantum efficiency could be increased by partial strain releasing to reduce piezoelectric field in the active layer. The thermal activation energy of a nanoporous structure (58.5 meV) is higher than the standard one (32.5 meV) from a temperature dependent PL measurement. The nanoporous InGaN-based LED structure have the blue shift phenomenon of electroluminescence (EL) emission spectrum and 31% light output power enhancement compared to the standard LED. The pattern nanoporous InGaN-based LED was treated through the PEC oxidation process to reduce the Schottky barrier height and increase light output power prevent from the thermal heat effect. The PEC oxidation process successfully reduced the operating voltage and thermal heat effect of the pattern-nanoporous LEDs for high efficiency nanoporous LEDs applications.