Laser-Crystallized Epitaxial Germanium on Silicon-Based Near-Infrared Photodetector

Kumari, K and Kumar, S and Mehta, M and Chatterjee, A and Selvaraja, SK and Avasthi, S (2022) Laser-Crystallized Epitaxial Germanium on Silicon-Based Near-Infrared Photodetector. In: IEEE Sensors Journal, 22 (12). pp. 11682-11689.

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Abstract

This work reports the fabrication of near-infrared (NIR) photodetectors based on laser-crystallized epitaxial germanium (100 nm) on silicon (001). The laser crystallized epitaxial germanium has an extracted dislocation density of ≈ 10 9 cm-2. Metal-Semiconductor-Metal photodetectors fabricated on these films using Cr/Au as contact showed remarkable responsivity values of 0.64 A/W at 1550 nm and 0.71 A/W at 1310 nm for a 1V bias. Au/Cr-Ge contact exhibited ohmic characteristics with a contact resistance of ≈ 340 ± 13~Ømega . The devices showed a time response with a rise time (10-90) of 3 s and fall time (90-10) of 5.2 s. The obtained high value of dark current is reduced by one order after passivating the Ge layer below contact with TiO2 (5 nm). TiO2 based devices showed a contact resistance of 3400± 283Ømega . Kelvin probe force microscopy (KPFM) was employed to map the surface potential across the MSM photodiodes to understand the current transport mechanisms. KPFM yields an Ohmic and Schottky contact in MSM diodes without and with TiO2 passivation layer, respectively. With further improvement in the device architecture; and optimization of the laser crystallization conditions of Ge film; these devices can be used as a potential candidate for various low-cost NIR applications, like on-chip integration of photonic circuits. © 2001-2012 IEEE.

Item Type:	Journal Article
Publication:	IEEE Sensors Journal
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to the Institute of Electrical and Electronics Engineers Inc.
Keywords:	Contact resistance; Dark currents; Infrared detectors; Passivation; Photons; Semiconductor lasers; Silicon; Titanium dioxide, Ge MSM IR photodetector; Ge-on-Si; Germanium on silicons; Germaniums (Ge); IR photodetectors; Kelvin probe force microscopy; Laser crystallization; Laser crystallization of ge-on-si; Near infrared photodetectors; Near-infrared sensors, Germanium
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	21 Sep 2022 09:51
Last Modified:	21 Sep 2022 09:51
URI:	https://eprints.iisc.ac.in/id/eprint/76701

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