Pyramid-shaped silicon photodetector with subwavelength aperture for NSOM

• Published in: IEEE transactions on electron devices Vol. 49; no. 6; pp. 986 - 990
• Main Authors: Chelly, R A, Cohen, Y, Sa' ar, A, Shappir, J
• Format: Journal Article
• Language: English
• Published: 01-06-2002
• Subjects: Anisotropy; Apertures; Devices; Ethylene; Photodetectors; Pyramids; Scanning; Silicon
• ISSN: 0018-9383
• DOI: 10.1109/TED.2002.1003717

We present a new type of silicon photodetector with a subwavelength aperture designed to scan material surfaces with a resolution inaccessible by conventional optical microscopy. Such a probe is designed for integration into a near-field scanning optical microscope (NSOM) for scanning and collecting information from the near-field region located at the vicinity of the surface. The photodetector, which was realized by conventional microelectronics technology, is located on top of a 250-mum-high pyramid, enabling detection of reflected as well as transmitted light. The light sensitive part of the probe consists of a micromachined silicon structure built using anisotropic etch solutions such as ethylene diamine pyrocatechol (EDP) and KOH. The shape of the probe is a truncated double pyramid with a ring shape top silicon/aluminum Schottky diode surrounding an exposed silicon photosensitive area of about 150 nm in diameter. Typical I-V characteristics and optical response measurements are presented