09:30 〜 11:30
▲ [15a-PB1-5] Fabrication of Silicon Nanowire Solar Cells by Metal Catalyzed Electroless Etching in HF Solution
キーワード：solar cell,nanowire
As a clean and renewable energy, solar energy has been bourgeoning advanced in the past several decades which the high cost bulk silicon (Si) solar mastered the major market due to its high efficiency. However in recent years, with enormous advantages of carrier collection and light absorption, Si nanowire (SiNW) solar cells offer a potential to replace the bulk Silicon solar cells.
SiNW arrays were prepared by Metal Catalyzed Electroless Etching (MCEE) on 525 µm-thick n-type single side polished crystalline Si (111) substrates. After pre-cleaning processes, vertically-aligned SiNW arrays were formed using different etching of (A) 3 min, (B) 5 min and (C) 30 min. Then, all samples were put into CVD chamber to fabricate solar cell junction by deposition of the B doped p-type Si shell layer. Finally, a finger grid pattern Al and full coverage Ag were sputtered for front electrode and back contact.
Cross-sectional SEM results of sample (A), (B), (C) show the SiNW arrays with average lengths of 500 nm (A), 750 nm (B), 6000 nm (C). It is obviously that the length of SiNW arrays are fully depend on the etching time. And Current density-Voltage was measured under 100 mW/cm2 illumination of an AM1.5 solar simulator. Comparing with the planar silicon solar cell, the efficiency increased from 1.8% to 3.9% for SiNW array solar cells (Sample (A) and (B)). These enhancements of performance is due to the short carrier collection lengths which reduce photo-generated carrier recombination. However, when the nanowire length increased up to 6000nm(C), JSC reduced less than half that of Sample (A) and (B), which is also lower than the planar solar cell. This degradation is caused by the increase in the surface states and interfacial dangling bond defects with increasing surface area of SiNWs. Some optional solutions such as hydrogen passivation and ozone treatments will be concentrated in the next step.
SiNW arrays were prepared by Metal Catalyzed Electroless Etching (MCEE) on 525 µm-thick n-type single side polished crystalline Si (111) substrates. After pre-cleaning processes, vertically-aligned SiNW arrays were formed using different etching of (A) 3 min, (B) 5 min and (C) 30 min. Then, all samples were put into CVD chamber to fabricate solar cell junction by deposition of the B doped p-type Si shell layer. Finally, a finger grid pattern Al and full coverage Ag were sputtered for front electrode and back contact.
Cross-sectional SEM results of sample (A), (B), (C) show the SiNW arrays with average lengths of 500 nm (A), 750 nm (B), 6000 nm (C). It is obviously that the length of SiNW arrays are fully depend on the etching time. And Current density-Voltage was measured under 100 mW/cm2 illumination of an AM1.5 solar simulator. Comparing with the planar silicon solar cell, the efficiency increased from 1.8% to 3.9% for SiNW array solar cells (Sample (A) and (B)). These enhancements of performance is due to the short carrier collection lengths which reduce photo-generated carrier recombination. However, when the nanowire length increased up to 6000nm(C), JSC reduced less than half that of Sample (A) and (B), which is also lower than the planar solar cell. This degradation is caused by the increase in the surface states and interfacial dangling bond defects with increasing surface area of SiNWs. Some optional solutions such as hydrogen passivation and ozone treatments will be concentrated in the next step.