Transient surface photovoltage studies of bare and Ni-filled porous silicon performed in different ambients

Abstract

Mesoporous silicon and porous silicon/Ni nanocomposites have been investigated in this work employing light-dark surface photovoltage (SPV) transients to monitor the response of surface charge dynamics to illumination changes. The samples were prepared by anodization of a highly n-doped silicon wafer and a subsequent electrodepositing of Ni into the pores. The resulting pores were oriented towards the surface with an average pore diameter of 60 nm and the thickness of the porous layer of approximately 40 μm. SPV was performed on a bare porous silicon as well as on a Ni-filled porous silicon in vacuum and in different gaseous environments (O2, N2, Ar). A significant difference was observed between the ‘light-on’ and ‘light-off’ SPV transients obtained in vacuum and those observed in gaseous ambiences. Such behavior could be explained by the contribution to the charge exchange in gas environments from chemisorbed and physisorbed species at the semiconductor surface.PACS81.05.Rm; 73.20.-r; 75.50.-y; 82.45.Yz

Z‐scheme SnS2/CsPbBr3 Heterojunctions for Photoreduction CO2 Reaction and Related Photoinduced Carrier Behaviors

“…Finally the SPV intensity increases again while pumping CO 2 into the testing system, indicating that CO 2 molecules can indeed adsorb on the CsPbBr 3 NC surface to capture photogenerated electrons from CsPbBr 3 NCs for the subsequent reduction reaction (Figure 6a). [37] For bulk SnS 2 , however, completely different phenomena are observed, whose positive SPV signals show that photogenerated holes prefer to flow to the SnS 2 surface under illumination, which cannot be utilized by CO 2 (Figure 6b). Instead, for the 2%SnS 2 /CsPbBr 3 NCs-60 composite sample, negative SPV signal intensity increases, suggesting that CO 2 molecules adsorbed on the CsPbBr 3 NC surface can interact with photogenerated electrons to accomplish the reduction reaction (Figure 6c).…”