Asymmetrically contacted germanium photodiode using a metal-interlayer-semiconductor-metal structure for extremely large dark current suppression

Hwan Jun Zang, Gwang Sik Kim, Gil Jae Park, Yong Soo Choi, Hyun-Yong Yu

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

In this study, we proposed germanium (Ge) metal-interlayer-semiconductor-metal (MISM) photodiodes (PD), with an anode of a metal-interlayer-semiconductor (MIS) contact and a cathode of a metal-semiconductor (MS) contact, to efficiently suppress the dark current of Ge PD. We selected titanium dioxide (TiO2) as an interlayer material for the MIS contact, due to its large valence band offset and negative conduction band offset to Ge. We significantly suppress the dark current of Ge PD by introducing the MISM structure with a TiO2 interlayer, as this enhances the hole Schottky barrier height, and thus acts as a large barrier for holes. In addition, it collects photo-generated carriers without degradation, due to its negative conduction band offset to Ge. This reduces the dark current of Ge MISM PDs by x8000 for 7-nm-thick TiO2 interlayer, while its photo current is still comparable to that of Ge metal-semiconductor-metal (MSM) PDs. Furthermore, the proposed Ge PD shows x6,600 improvement of the normalized photo-to-dark-current ratio (NPDR) at a wavelength of 1.55 μm. The proposed Ge MISM PD shows considerable promise for low power and high sensitivity Ge-based optoelectronic applications.

Original languageEnglish
Pages (from-to)3686-3689
Number of pages4
JournalOptics Letters
Volume41
Issue number16
DOIs
Publication statusPublished - 2016 Aug 15

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Germanium
Semiconductors
dark current
photodiodes
interlayers
germanium
Metals
retarding
metals
Electrodes
conduction bands
titanium oxides

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Asymmetrically contacted germanium photodiode using a metal-interlayer-semiconductor-metal structure for extremely large dark current suppression. / Zang, Hwan Jun; Kim, Gwang Sik; Park, Gil Jae; Choi, Yong Soo; Yu, Hyun-Yong.

In: Optics Letters, Vol. 41, No. 16, 15.08.2016, p. 3686-3689.

Research output: Contribution to journalArticle

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