Test of the thermal equilibration model for persistent photoconductivity in doping-modulated amorphous silicon.
The persistent photoconductivity effect in doping modulated amorphous silicon is compared to the light-induced conductivity changes in compensated amorphous silicon. The recent proposal that the defect structure of doped amorphous silicon is in metastable thermal equilibrium is able to account for the metastable excess conductivity in both systems, and for the several orders of magnitude difference in exposure times needed.
Factors affecting light-induced excess conductivity in doping-modulated amorphous silicon superlattices
Doping‐modulated amorphous silicon semiconducting films which exhibit the phenomenon of light‐induced excess conductivity (LEC) have been made by silane glow discharge in a single‐chamber system. This phenomenon shows a strong dependence on substrate temperature and process gas composition. The LEC effect decreases for very small and very large layer thickness. There also seems to be an optimum defect density for producing large effects.
Preparation of hydrophilic poly(vinyl butyral) hollow fiber membrane via thermally induced phase separation
Abstract Hydrophilic microporous hollow fiber membranes were prepared via thermally induced phase separation (TIPS). Poly(vinyl butyral) (PVB) and three kinds of polyethylene glycols (PEG) with the molecular weight of 200, 400 and 600 were used as polymer and diluents. In all cases, liquid–liquid (L–L) phase separation occurred and asymmetric cellular structures with the smaller pores at the outer surface were obtained. The properties of membranes such as pore size, water permeability, solute rejection and intensity were investigated by changing molecular weight of PEG, concentration of PVB, composition of the bath and air gap distance. The smaller molecular weight of PEG, the more PEG in the bath and the shorter air gap distance resulted in the higher water permeability, the lower solute rejection property and the lower mechanical strength.