Method for forming optical aperture, near- field optical head, method for fabricating near-field optical head, and information recording/reading apparatus

摘要

An insulated gate transistor has a semiconductor thin film having a first main surface and a second main surface, a first gate insulating film formed on the first main surface of the semiconductor thin film, a first conductive gate formed on the first gate insulating film, first and second confronting semiconductor regions of a first conductivity type insulated from the first conductive gate and disposed in contact with the semiconductor thin film, and a third semiconductor region of a second conductivity type opposite to the first conductivity type disposed in contact with the semiconductor thin film. A gate threshold voltage of the first conductive gate is controlled by a forward bias of the third semiconductor region with respect to one of the first and second semiconductor regions.