Fabrication and characterization of PIN and MWQ GaN/InGaN solar cell

• Main Authors: Yu Lin Lee, 李育箖
• Other Authors: L. B. Chang
• Format: Others
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/54897723000136902809

博士 === 長庚大學 === 電子工程學研究所 === 98 === Recently, indium gallium nitride materials (InxGa1−xN) have been extensively investigated for application in photovoltaic devices owing to their energy bandgaps lying between 0.7 and 3.4 eV. The properties of the wide bandgap range make it useful for the fabrication of high performance multi-junction solar cells. In theory, an efficiency of about 46% is achievable for a seven junctions with the photocurrent density was 8.33 mA/cm2 and the open-circuit voltage was 6.26 V. And it will be reached 62% for 4 junctions tandem cell at concentration of 500x. Many optoelectronic researchers focus their studies on the theoretical development of efficiency performance in InGaN solar cells, but few of them employed epitaxial growth system to realize device fabrication and related simulator measurement. In this work, P-I-N and MQW structures GaN/InxGa1-xN solar cells with inter-digital shaped Ti/Au electrodes are fabricated and measured under a standard measurement condition of AM 1.5G solar spectrum. A Ohmic conducting Ni/Au oxidation layer is adopted to reduce Schottky contact loss between the p-GaN top layer and the Ti/Au electrode. High Voc of In0.2Ga0.8N and In0.28Ga0.72N multiple quantum well solar cells are experimentally obtained (2.2V and 1.8V, respectively). This obtained efficiency increases with temperatures up to 100 ◦C and then decreases due to competing results between the reduction in Voc and an increase in Jsc. There are two new structures to enhance the light absorption efficiency. First new structure is the flip chip (FC) structure and the second new one is a reflective structure. With compare to the traditional device, both the FC device and the reflective one all exhibited larger short current density and improved efficiency. The improve factor of efficiency, with corresponding to the proposed FC structure one and the reflective one in In0.2Ga0.8N MQWSCs are 1% and 10%. Again, in In0.28Ga0.72N MQWSCs, also the correspondent value also increases from 1% and 4%.