Improved Optoelectronic Characteristics of GaN-Based Devices with Periodic Dielectric Structures and Quantum Well Structure Design by Metalorganic Vapor Phase Epitaxy

• Main Authors: Ya-YuYang, 楊亞諭
• Other Authors: Wei-Chih Lai
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/40852328250448536369

博士 === 國立成功大學 === 光電科學與工程學系 === 101 === In this dissertation, growth and fabrication of III-nitride-based optoelectronic devices by Metal Organic Vapor Phase Epitaxial (MOVPE) have been studies. We achieved a small reverse leakage current because of the quality improvement of the lateral growth-induced crystal. Similar random scattering of light can be achieved by the embedded SiO2 pillars and air gap array structures. First, we improved the External Quantum Efficiency (IQE) by embedded SiO2 pillars and air gap array structures in u-GaN layers. In our study, the embedded 500 nm height SiO2 pillars and air gap array structures could enhance Light-Emitting Diode (LED) output power by more than 50% due to the enhanced guided-light scattering efficiency in our study. With the combination of air gap array and Patterned Sapphire Substrate (PSS), we achieved a small reverse leakage current. The study also reveals that the LED with combined air gap array and PSS exhibited the largest IQE and Light Extraction Efficiency (LEE) enhancements 9.6% and 43.8%, respectively. In our study, we also demonstrate the light output power enhancement and conversion efficiency enhancement of thick well short-period InGaN/GaN MQW LEDs and Solar Cells (SCs) with thickness-fluctuated InGaN well with H2 in GaN barrier spacer layer. Consequently, the thick well short-period InGaN/GaN MQW LEDs with thickness-fluctuated InGaN well that were fabricated in this study had a 20-mA output power enhancement of 25.6% and a decreased efficiency droop from 55.0% to 36.7% compared with traditional long-period InGaN/GaN MQW LEDs. The power conversion efficiency (η%) of thick-well InGaN/GaN SPMQW SCs with H2 on PSS (1.36%) showed a 76.6% increase compared with thick-well InGaN/GaN SPMQW SCs with H2 on plane sapphire (0.77%).