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-μm-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.
Bibliographical noteFunding Information:
Manuscript received October 8, 2001; revised February 22, 2002. This work was supported by the Israeli 0.25 Micron Consortium. The review of this paper was arranged by Editor P. Bhattacharya. The authors are with the Department of Applied Physics, The Fredy and Nadine Herman Graduate School of Applied Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Publisher Item Identifier S 0018-9383(02)04877-3.
- Near-field optical microscopy
- Schottky photodiode
- Wet anisotropic etch