Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7134101 | Sensors and Actuators A: Physical | 2017 | 7 Pages |
Abstract
A linear array of 55 butt-coupled three-dimensional (3D) photodetectors based on a silicon (Si) substrate is presented with a monolithically integrated tapered U-grooves platform for embedding strands of a fiber bundle into a Si chip. This structure enables a direct coupling of the fiber strands with a diameter of Ã30 μm to the vertical photoactive areas of a Si detector array one by one. A vertically 3D large photoactive area â¼30 μm Ã 40 μm + 2(30 μm Ã 10 μm) is formed separated from the n-i-p structure on the top side to achieve a high performance butt-coupled photodetector. The prototype is fabricated by employing 3D CMOS and MEMS technology on a p-type Si wafer. The implementation of 30 μm-deep double-trench isolation with the formation of a shallow n+-p junction and SiO2-liner over the trench sidewalls as well as SU-8 filling of the trenches realizes a high efficiency detector isolation and a low dark current of 1.14 nA at 2 V reverse bias. The maximum photoresponsivities under illumination with 470 nm, 525 nm, and 631 nm LEDs light are observed under the lowest incident light power. A low junction capacitance of â¼30+/â3fF at 2.4 V reverse bias is measured at a frequency of 1 MHz. Therefore, this approach brings outstanding features for non-telecom and high efficiency remote optical fiber sensor applications at the wavelengths of 470 nm, 525 nm, and 631 nm in high electromagnetic field environments.
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Authors
Iman Sabri Alirezaei, Joerg Vierhaus, Edmund P. Burte,