US-12624988-B2 - Electromagnetic wave detector and electromagnetic wave detector array

US12624988B2US 12624988 B2US12624988 B2US 12624988B2US-12624988-B2

Abstract

An electromagnetic wave detector includes a semiconductor layer, a two-dimensional material layer, a first electrode portion, a second electrode portion, and a ferroelectric layer. Two-dimensional material layer is electrically connected to semiconductor layer. First electrode portion is electrically connected to two-dimensional material layer. Second electrode portion is electrically connected to two-dimensional material layer with semiconductor layer interposed therebetween. Ferroelectric layer is electrically connected to at least any one of first electrode portion, second electrode portion and semiconductor layer. Electromagnetic wave detector is configured such that an electric field generated from ferroelectric layer is shielded with respect to two-dimensional material layer. Alternatively, ferroelectric layer is arranged so as not to be overlapped with two-dimensional material layer in plan view.

Inventors

Masaaki Shimatani
Shimpei OGAWA
Shoichiro FUKUSHIMA
Satoshi Okuda

Assignees

MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date: 20260512
Application Date: 20210824
Priority Date: 20201026

Claims (20)

1 . An electromagnetic wave detector comprising: a semiconductor layer; a two-dimensional material layer electrically connected to the semiconductor layer; a first electrode portion electrically connected to the two-dimensional material layer; a second electrode portion electrically connected to the two-dimensional material layer with the semiconductor layer interposed between the second electrode portion and the two-dimensional material layer; an insulating film that is arranged on the semiconductor layer, and is provided with an opening; and a ferroelectric layer electrically connected to at least any one of the first electrode portion, the second electrode portion and the semiconductor layer, the ferroelectric layer being arranged such that resistance between the first electrode portion and the second electrode portion changes when polarization inside the ferroelectric layer is changed by application of an electromagnetic wave, an electric field generated from the ferroelectric layer being shielded with respect to the two-dimensional material layer, a Fermi level of the two-dimensional material layer being configured so as not to be changed by an electric field effect of an electric field generated from the ferroelectric layer, or the ferroelectric layer being arranged so as not to be overlapped with the two-dimensional material layer in plan view, and the two-dimensional material layer is electrically connected to the semiconductor layer in the opening, and extends from above the opening to the insulating film.
2 . The electromagnetic wave detector according to claim 1 , wherein the first electrode portion has an annular shape in plan view, the semiconductor layer is exposed from the insulating film on an inner side than the first electrode portion, and the two-dimensional material layer is electrically connected to the semiconductor layer on an inner side than the first electrode portion.
3 . The electromagnetic wave detector according to claim 1 , wherein a gap is provided between the insulating film and the two-dimensional material layer.
4 . The electromagnetic wave detector according to claim 1 , further comprising at least one of a voltmeter and an ammeter, wherein the two-dimensional material layer, the first electrode portion, the second electrode portion and the semiconductor layer are electrically connected in an order of the first electrode portion, the two-dimensional material layer, the semiconductor layer and the second electrode portion, and at least one of the voltmeter and the ammeter is configured to detect an electromagnetic wave by detecting change in at least one of voltage of a current and a current flowing between the first electrode portion and the second electrode portion.
5 . The electromagnetic wave detector according to claim 1 , further comprising a tunnel insulating layer, the tunnel insulating layer being sandwiched between the two-dimensional material layer and the semiconductor layer.
6 . The electromagnetic wave detector according to claim 1 , further comprising a connection conductor, wherein the two-dimensional material layer is electrically connected to the semiconductor layer with the connection conductor interposed between the two-dimensional material layer and the semiconductor layer.
7 . The electromagnetic wave detector according to claim 1 , wherein the two-dimensional material layer includes a plurality of first parts arranged on the semiconductor layer, and the plurality of first parts are arranged at an interval from each other.
8 . The electromagnetic wave detector according to claim 1 , wherein the two-dimensional material layer includes a plurality of second parts arranged on the first electrode portion, and the plurality of second parts are arranged at an interval from each other.
9 . The electromagnetic wave detector according to claim 1 , wherein the ferroelectric layer includes a first ferroelectric part and a second ferroelectric part, and each of the first ferroelectric part and the second ferroelectric part is electrically connected to the two-dimensional material layer and the semiconductor layer.
10 . The electromagnetic wave detector according to claim 9 , wherein a wavelength of electromagnetic wave capable of being absorbed by the first ferroelectric part is different from a wavelength of electromagnetic wave capable of being absorbed by the second ferroelectric part.
11 . The electromagnetic wave detector according to claim 9 , wherein a polarizability of the first ferroelectric part is different from a polarizability of the second ferroelectric part.
12 . The electromagnetic wave detector according to claim 1 , wherein the semiconductor layer includes a first semiconductor part and a second semiconductor part having a conductive type different from a conductive type of the first semiconductor part, and the first semiconductor part is joined with the second semiconductor part.
13 . The electromagnetic wave detector according to claim 1 , wherein the two-dimensional material layer includes a turbostratic structure part.
14 . The electromagnetic wave detector according to claim 1 , further comprising a contact layer, the contact layer being arranged to be in contact with the two-dimensional material layer.
15 . The electromagnetic wave detector according to claim 1 , further comprising a conductor, the conductor being arranged to be in contact with the two-dimensional material layer.
16 . The electromagnetic wave detector according to claim 15 , wherein the conductor includes a plurality of conductive parts, and the plurality of conductive parts are arranged at an interval from each other.
17 . The electromagnetic wave detector according to claim 1 , further comprising a substrate portion, wherein the two-dimensional material layer, the first electrode portion and the ferroelectric layer are arranged on the substrate portion.
18 . An electromagnetic wave detector array comprising a plurality of the electromagnetic wave detectors according to claim 1 , the plurality of electromagnetic wave detectors being arranged side by side along at least one of a first direction and a second direction intersecting the first direction.
19 . The electromagnetic wave detector according to claim 1 , wherein at least any one of the first electrode portion, the second electrode portion, and the semiconductor layer is sandwiched between the ferroelectric layer and the two-dimensional material layer.
20 . The electromagnetic wave detector according to claim 1 , wherein the two-dimensional material layer contacts a top surface of the semiconductor layer and a top surface of the first electrode portion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is based on PCT filing PCT/JP2021/030923, filed Aug. 24, 2021, which claims priority to JP 2020-178997, filed Oct. 26, 2020, the entire contents of each are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to an electromagnetic wave detector and an electromagnetic wave detector array. BACKGROUND ART As a material of an electromagnetic wave detecting layer for use in a next-generation electromagnetic wave detector, graphene which is one example of a two-dimensional material layer is known. Graphene has very high mobility. Absorptance of graphene is as low as 2.3%. For this reason, a technique of enhancing the sensitivity in an electromagnetic wave detector in which graphene is used as a two-dimensional material layer has been proposed. For example, U.S. Patent Application Publication 2015/0243826 (PTL 1) proposes a detector having the following structure. That, in U.S. Patent Application Publication 2015/0243826, two or more dielectric layers are disposed on the n-type semiconductor layer. A graphene layer is formed on two dielectric layers, and on a surface part of an n-type semiconductor layer located between the two dielectric layers. Source and drain electrodes connected to both ends of the graphene layer are arranged on the dielectric layer. The gate electrode is connected to the n-type semiconductor layer. In the aforementioned detector, voltage is applied to the graphene layer serving as a channel via the source and drain electrodes. As a result, the photo carrier generated in the n-type semiconductor layer is amplified, and thus the sensitivity of the detector improves. When voltage is applied to the gate electrode, and the source electrode or the drain electrode, OFF operation is enabled by Schottky connection between graphene and the n-type semiconductor layer. CITATION LIST Patent Literature PTL 1: U.S. Patent Application Publication 2015/0243826 SUMMARY OF INVENTION Technical Problem In the detector described in the above publication (electromagnetic wave detector), an electromagnetic wave is detected by a photo carrier generated by application of the electromagnetic wave to the semiconductor layer. Therefore, the sensitivity of the detector depends on the quantum efficiency of the semiconductor layer. The quantum efficiency of the semiconductor layer is not sufficiently high depending on the wavelength of the electromagnetic wave. Therefore, the detection sensitivity of the electromagnetic wave detector is insufficient. The present disclosure was made in light of the above problems, and it is an object of the present disclosure to provide an electromagnetic wave detector and an electromagnetic wave detector array capable of improving the sensitivity. Solution to Problem An electromagnetic wave detector of the present disclosure includes a semiconductor layer, a two-dimensional material layer, a first electrode portion, a second electrode portion, and a ferroelectric layer. The two-dimensional material layer is electrically connected to the semiconductor layer. The first electrode portion is electrically connected to the two-dimensional material layer. The second electrode portion is electrically connected to the two-dimensional material layer with the semiconductor layer interposed therebetween. The ferroelectric layer is electrically connected to at least any one of the first electrode portion, the second electrode portion, and the semiconductor layer. The electromagnetic wave detector is configured such that the electric field generated from the ferroelectric layer is shielded with respect to the two-dimensional material layer. Alternatively, the ferroelectric layer is arranged so as not to be overlapped with the two-dimensional material layer in plan view. Advantageous Effects of Invention According to the electromagnetic wave detector of the present disclosure, the ferroelectric layer is electrically connected to at least any one of the first electrode portion, the second electrode portion, and the semiconductor layer. The pyroelectric effect of the ferroelectric layer does not depend on the wavelength of the electromagnetic wave. Therefore, the sensitivity of the electromagnetic wave detector does not depend on the quantum efficiency of the semiconductor layer. Therefore, even for a wavelength for which the quantum efficiency of the semiconductor layer decreases, deterioration in sensitivity of the electromagnetic wave detector is suppressed. Therefore, the sensitivity of the electromagnetic wave detector improves. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a section view schematically showing a configuration of an electromagnetic wave detector according to Embodiment 1. FIG. 2 is a top view schematically showing a configuration of the electromagnetic wave detector according to Embodiment 1. FIG. 3 is a section view schematically showing a configuration of an electromagnetic wave detector according