Investigation of silicon base p-NiO/n-Si heterojunction solar cells

• Main Authors: Yu-Song Cheng, 鄭育松
• Other Authors: Na-Fu Wang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/68835472577227961181

碩士 === 正修科技大學 === 電子工程研究所 === 101 === This study reports the fabrication of p-type Ni1-xO:Li/n-Si heterojunction solar cells (HJSCs) by depositing Li-doped Ni1-xO (p-Ni1-xO:Li) on a n-Si substrate (P+/n) using RF magnetron sputtering. The main investigation in this study will divide two parts. Firstly, films deposited on glass and silicon substrates at various working pressures (partial pressure of argon) and temperatures were first analyzed to estimate the optoelectrical properties of p-Ni1-xO: Li thin films. According to the results of experiments, the Ni1-xO:Li thin films deposited at 6 mTorr and 300℃ showed the best crystallization, the high carrier concentration of 1.28×1018 cm-3, high work function 5.32 eV and refractive index of 2.54. The p-Ni1-xO:Li thin film not only acts an emitter layer, but also acts an antireflective coating thin film. The second parts investigate the influence of conversion efficiency of Ni1-xO:Li/n-Si heterojunction solar cell. The initial efficiency is 1.34% (Voc:0.370 V, Jsc:12.354 mA/cm2, FF:0.294, Rs:22.05 Ω and Rsh:360 Ω). The low efficiency can be attributed to the high resistivity of Ni1-xO:Li thin film (2.7 Ω-cm) and thicker SiOx layer (27.78 Å) at interface. In order to solve the problem, a high conductivity n-AZO thin films has been deposited on the p-Ni1-xO:Li thin film as a front electrode contact layer. Thus, the efficiency of cell elevates to 2.33% (Voc:0.354 V, Jsc:22.084 mA/cm2, FF:0.307, ɳ:2.33%, Rs:10.81 Ω, Rsh:320 Ω). Finally, process parameters will be optimized by varying substrate temperature from 300℃ to RT, results to SiOx thickness reduces. Thus, it is shown the best efficiency of 4.89 % (Voc:0.363 V, Jsc:26.452 mA/cm2, FF:0.508) in this study. The dark IV characteristics exhibit the diode ideal factor and leakage current density is approximately 2.33 and 4x10-7 A/cm2, respectively. This study proposes that reduce interface states and improve the optoelectrical properties of p-NiO are two important issues because they can directly and significantly affect the conversion efficiency of p-Ni1-xO:Li/n-Si HJSC. Keywords: heterojunction, nickel oxide, solar cells, sputtering