多孔质半导体及其制造方法

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This invention provides a filter capable of performing collection of organic materials, bacteria, viruses and other hazardous materials and sterilization/decomposition of collected matter at low cost with extremely high efficiency; and a process for producing the same. In particular, a porous semiconductor constituted of a semiconductor material capable of light emission is formed inside or on the surface of a porous ceramic or metal as a substrate. Electrodes are fitted thereto to thereby obtain a filter. Fluid is filtered while applying voltage so as to emit ultraviolet radiation. Thus, sterilization/decomposition of hazardous materials, etc. can be performed simultaneously with the filtration thereof. The porous semiconductor layer is preferably includes pillars perpendicularly grown to the substrate face and characterized in generating ultraviolet lights with a wavelength below 400 nm. The fine holes of the porous substrate pillars are through holes perpendicular to the substrate face with an average pore size of 0.1 to 100 mum. The tips of the pillars are preferably acute. During production, the porous substrate is used as a filtration material to filter a suspension solution containing luminous semiconductor particles and form a stack layer of semiconductor particles on the surface of the porous substrate. Furthermore, a stack layer of p-type semiconductor particles and a stack layer of n-type semiconductor particles can also be formed to form a pn connection. Moreover, the porous semiconductor is characterized in that : an insulative layer is formed on the top face and the bottom face of the porous semiconductor layer, semiconductor particles are dispersed in the insulative layer, and the band gap of the semiconductor particles in the porous semiconductor layer or the porous luminous layer is over 3.2 eV and the semiconductor particles are doped with predominantly luminous gadolinium. Furthermore, the porous semiconductor is characterized in that : the porous semiconductor layer includes a silicon nitride porous matter formed of pillar silicon nitride particles with an aspect ratio of over 3 and at least one type of oxide of a rare earth element and capable of radiating visible or ultraviolet light.