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MICRO INTERFEROMETER BASED ON AMORPHOUS SILICON NANOSENSOR

E. Bunte1, K. H. Jun1, H. Stiebig1,*

Affiliation

  1. Institute of Photovoltaics, Research Center Jülich, D-52425 Jülich, Germany

Abstract

Length measurement with nm-accuracy can be carried out by means of a new phase selective partly transparent detector (PSTD). The working principle bases on the sampling of a standing wave created in front of a movable mirror. The pivotal element of the set-up is the developed nanosensor - a thin stack of two almost transparent photodiodes of amorphous silicon deposited on a glass substrate. The two photodiodes measure the intensity of an optical standing wave by means of absorption layers with thicknesses below 50 nm and thus, provide two photocurrents which are proportional to the intensity at their individual positions. The design of the multi layer stack has to be optimized regarding high transmittance, minimized distortions of the standing wave, and a phase shift of 90° between the photocurrents of the two diodes. Different concepts to adjust the phase shift between the photocurrents of the two diodes without deteriorating the other conditions were studied by means of optical simulations. Lissajous figures close to a perfect circle are recorded to demonstrate the operation principle of the new device. Further aspects to improve the performance of the PSTD will be discussed..

Keywords

Micro interferometer, Amorphous silicon, Nanosensor.

Submitted at: May 19, 2005
Accepted at: July 21, 2005

Citation

E. Bunte, K. H. Jun, H. Stiebig, MICRO INTERFEROMETER BASED ON AMORPHOUS SILICON NANOSENSOR, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 4, pp. 1899-1907 (2005)