Preparation and Study of Nano-Porous-Silicon (NPS) for Applications on Photo-Voltaic Devices

• Main Authors: Che-Wei Lin, 林哲緯
• Other Authors: Kuen-Hsien Wu
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/91312812016404823761

碩士 === 南台科技大學 === 光電工程系 === 97 === Due to the controllable optoelectronic characteristics of porous silicon such as modulation of energy gap、refractive index changes, this material has much potential in applications of optoelectronic devices. In this paper, we used electrochemical etching techniques to prepare nano-porous-silicon (NPS) structures on silicon substrates. Optoelectronic characteristics of these as-formed NPS serving as light-absorption layers and light-reflection layers of photo-voltaic devices had been measured and analyzed, respectively. N-type, (100) silicon wafers with resistivity of 1-10Ω-cm and 0.001-0.003Ω-cm were used for starting materials. From the experimental processes, we found that to prepare NPS with controllable structures and with much higher reproducibility, heavily doped silicon wafers (0.001-0.003Ω-cm) were more preferred. When NPS structures acted as light-absorption layers, devices with NPS layers of 70% porosity got 40nm and 100nm increases in FWHM of responsivity spectra and 3.57-time and 25-time larger conversion efficiency as compared to those with porosity of 55% and 20% respectively. While working as the internal light-reflection layers of devices, NPS layers with low/high-porosity double-layered structures showed 8% higher reflectivity in near-infrared (0.8~1um) ranges than that of single-layered NPS structures. From the experimental results, we found that NPS structures with higher porosity can get higher light-absorption efficiency when acting as light-absorption layers. While working as the internal light-reflection layers of devices, multi-layered NPS structures with larger differences in high/low porosity and more numbers of periods of high/low porosity exhibited higher reflectivity. Therefore, we believe NPS structures has much potential in applications on photo-voltaic devices.