Enhancing Water-Splitting Efficiency Using a Zn/Sn-Doped PN Photoelectrode of Pseudocubic alpha-Fe(2)O(3)Nanoparticles
NANOSCALE RESEARCH LETTERS
Authors: Yang, Jie-Xiang; Meng, Yongtao; Tseng, Chuan-Ming; Huang, Yan-Kai; Lin, Tung-Ming; Wang, Yang-Ming; Deng, Jin-Pei; Wu, Hsiang-Chiu; Hung, Wei-Hsuan
alpha-Phase hematite photoelectrodes can split water. This material is nontoxic, inexpensive, and chemically stable; its low energy gap of 2.3 eV absorbs light with wavelengths lower than 550 nm, accounting for approximately 30% of solar energy. Previously, we reported polyhedral pseudocubic alpha-Fe(2)O(3)nanocrystals using a facile hydrothermal route to increase spatial charge separation, enhancing the photocurrent of photocatalytic activity in the water-splitting process. Here, we propose a p-n junction structure in the photoanode of pseudocubic alpha-Fe(2)O(3)to improve short carrier diffusion length, which limits its photocatalytic efficiency. We dope Zn on top of an Fe(2)O(3)photoanode to form a layer of p-type semiconductor material; Sn is doped from the FTO substrate to form a layer of n-type semiconductor material. The p-n junction, n-type Fe2O3:Sn and p-type Fe2O3:Zn, increase light absorption and charge separation caused by the internal electric field in the p-n junction.
Fabrication of Nanocrystalline Silicon Thin Films Utilized for Optoelectronic Devices Prepared by Thermal Vacuum Evaporation
Authors: Ghazala, Magdy S. Abo; Othman, Hosam A.; El-Deen, Lobna M. Sharaf; Nawwar, Mohamed A.; Kashyout, Abd El-hady B.
Metal-induced crystallization of amorphous silicon is a promising technique for developing high-quality and cheap optoelectronic devices. Many attempts tried to enhance the crystal growth of polycrystalline silicon via aluminum-induced crystallization at different annealing times and temperatures. In this research, thin films of aluminum/silicon (Al/Si) and aluminum/silicon/tin (Al/Si/Sn) layers were fabricated using the thermal evaporation technique with a designed wire tungsten boat. MIC of a:Si was detected at annealing temperature of 500 degrees C using X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy. The crystallinity of the films is enhanced by increasing the annealing time. In the three-layer thin films, MIC occurs because of the existence of both Al and Sn metals forming highly oriented (111) silicon. Nanocrystalline silicon with dimensions ranged from 5 to 300 nm is produced depending on the structure and time duration. Low surface reflection and the variation of the optical energy gap were detected using UV-vis spectroscopy. Higher conductivities of Al/Si/Sn films than Al/Si films were observed because of the presence of both metals. Highly rectifying ideal diode manufactured from Al/Si/Sn on the FTO layer annealed for 24 h indicates that this device has a great opportunity for the optoelectronic device applications.