Silicon carbide-based full-spectrum-responsive photodetector and method for producing same

Abstract

The present application relates to semiconductor photodetectors, in particular to a silicon carbide-based UV-visible-NIR full-spectrum-responsive photodetector and a method for fabricating the same. The photodetector includes a silicon carbide substrate, and metal counter electrodes and a surface plasmon polariton nanostructure arranged thereon. The silicon carbide substrate and the metal counter electrodes constitute a metal-semiconductor-metal photodetector with coplanar electrodes. When the ultraviolet light is input, free carriers directly generated in silicon carbide are collected by an external circuit to generate electrical signals. When the visible light is input, hot carriers generated in the surface plasmon polariton nanostructure tunnel into the silicon carbide semiconductor to become free carriers to generate electrical signals.

Claims

1. A silicon carbide-based full-spectrum-responsive photodetector, comprising: a silicon carbide substrate; wherein a silicon surface of the silicon carbide substrate is provided with a plurality of metal counter electrodes and a surface plasmon polariton nanostructure; the plurality of metal counter electrodes are arranged on the silicon carbide substrate; the surface plasmon polariton nanostructure is arranged between the plurality of metal counter electrodes; the surface plasmon polariton nanostructure comprises a plurality of metal nanoparticles uniformly distributed on the silicon surface of the silicon carbide substrate; and a Schottky contact is formed between the plurality of metal counter electrodes and the silicon carbide substrate; wherein the surface plasmon polariton nanostructure is an array structure of the plurality of metal nanoparticles; the array structure of the plurality of metal nanoparticles has a period of 50-1000 nm; the plurality of metal nanoparticles are cubic nanoparticles or cylindrical nanoparticles; the plurality of metal nanoparticles have a side length of 20-500 nm or a diameter of 20-500 nm; and the plurality of metal nanoparticles each have a height of 20-500 nm.

2. The silicon carbide-based full-spectrum-responsive photodetector of claim 1, wherein the plurality of metal counter electrodes are interdigital electrodes; and the surface plasmon polariton nanostructure is uniformly distributed between the interdigital electrodes.

3. The silicon carbide-based full-spectrum-responsive photodetector of claim 2, wherein the silicon carbide substrate is made of a semi-insulating 4H-SiC, and has an intrinsic carrier concentration of 1e13/cm.sup.3-1e15/cm.sup.3 and a thickness of 100-800 μm; the plurality of metal counter electrodes are made of gold, silver, titanium, nickel, palladium or cadmium; and the interdigital electrodes each have a finger width of 100-300 μm, a finger spacing of 100-300 μm, an effective area of 0.1 cm.sup.2 and 5-15 pairs of electrodes.

4. The silicon carbide-based full-spectrum-responsive photodetector of claim 1, wherein the plurality of metal counter electrodes are Cr/Pd double-layer electrodes or Ag/Ti double-layer electrodes.

5. The silicon carbide-based full-spectrum-responsive photodetector of claim 1, wherein the plurality of metal nanoparticles each have a Cr/Au double-layer structure.

6. A silicon carbide-based full-spectrum-responsive photodetector, comprising: a silicon carbide substrate; wherein a silicon surface of the silicon carbide substrate is provided with a plurality of metal counter electrodes and a surface plasmon polariton nanostructure; the plurality of metal counter electrodes are arranged on the silicon carbide substrate; the surface plasmon polariton nanostructure is arranged between the plurality of metal counter electrodes; the surface plasmon polariton nanostructure comprises a plurality of metal nanoparticles uniformly distributed on the silicon surface of the silicon carbide substrate; and a Schottky contact is formed between the plurality of metal counter electrodes and the silicon carbide substrate; wherein the surface plasmon polariton nanostructure is a randomly-distributed island-shaped metal nanoparticle structure formed by annealing of a metal film; metal islands of the randomly-distributed island-shaped metal nanoparticle structure have an average diameter of 20-100 nm; and an average size of a gap between the metal islands is 50-300 nm.

7. A method of producing a silicon carbide-based full-spectrum-responsive photodetector, the silicon carbide-based full-spectrum-responsive photodetector comprising: a silicon carbide substrate; wherein a silicon surface of the silicon carbide substrate is provided with a plurality of metal counter electrodes and a surface plasmon polariton nanostructure; the plurality of metal counter electrodes are arranged on the silicon carbide substrate; the surface plasmon polariton nanostructure is arranged between the plurality of metal counter electrodes; the surface plasmon polariton nanostructure comprises a plurality of metal nanoparticles uniformly distributed on the silicon surface of the silicon carbide substrate; and a Schottky contact is formed between the plurality of metal counter electrodes and the silicon carbide substrate; the method comprising: (S1) calibrating a carbon surface and the silicon surface of the silicon carbide substrate by using an atomic force microscope; and cleaning and drying the silicon carbide substrate; (S2) distributing the plurality of metal nanoparticles evenly on the silicon surface of the silicon carbide substrate to form the surface plasmon polariton nanostructure; and (S3) preparing the plurality of metal counter electrodes on both sides of the surface plasmon polariton nanostructure to produce the silicon carbide-based full-spectrum-responsive photodetector.

8. The method of claim 7, wherein the step (S2) is performed through steps of: putting the silicon carbide substrate into a magnetron sputtering coating chamber; coating a gold film with a thickness of 5 nm by sputtering at a rate of 0.1 nm/s on a side of the silicon carbide substrate where the silicon surface is located; transferring the silicon carbide substrate coated with the gold film to a muffle furnace; heating the muffle furnace to 500° C.; and cooling the muffle furnace to room temperature in an equal step manner within two hours to form island-shape gold nanoparticles; and the step (S3) is performed through steps of: loading a mask on the silicon carbide substrate, and depositing a metal layer on the silicon carbide substrate by evaporation; and removing the mask to complete a preparation of the plurality of metal counter electrodes.

9. The method of claim 7, wherein the step (S2) is performed through steps of: coating a polymethyl methacrylate (PMMA) photoresist film with a thickness of 80 nm on the silicon surface of the silicon carbide substrate through spin coating; and exposing the silicon carbide substrate coated with the PMMA photoresist film by deep ultraviolet lithography or electron beam lithography; wherein an exposure pattern is consistent with a pattern of the surface plasmon polariton nanostructure; immersing the silicon carbide substrate into a developer solution for fixing followed by rinsing and blow drying; and producing a Cr adhesion layer with a thickness of 5 nm and an Au film with a thickness of 50 nm on a surface of the silicon carbide substrate by magnetron sputtering; immersing the silicon carbide substrate in acetone to peel off unexposed PMMA photoresist and Cr and Au thereon; and subjecting the silicon carbide substrate to blow drying to complete preparation of the surface plasmon polariton nanostructure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates structure of a metal-semiconductor-metal silicon carbide-based ultraviolet photodetector with coplanar electrodes in the prior art;

(2) FIG. 2 depicts structure of a silicon carbide-based full-spectrum-responsive photodetector according to Embodiment 1 of the present application, where the responsivity is made by fabricating metal counter electrodes and a surface plasmon nanostructure on a silicon carbide substrate;

(3) FIG. 3 is a cross-sectional view of the silicon carbide-based full-spectrum-responsive photodetector according to Embodiment 1 of the present application;

(4) FIG. 4A is an SEM morphologic image of the surface plasmon polariton nano-island structure prepared by annealing, where an average diameter of the nano-island structure is 40 nm;

(5) FIG. 4B shows transient photocurrent response characteristics of the silicon carbide-based ultraviolet-visible-near-infrared full-spectrum-responsive photodetector according to an embodiment of the present application, where the transient photocurrent response characteristics are measured at 375 nm, 660 nm, 850 nm, 1310 nm and 1550 nm, respectively;

(6) FIG. 5 illustrates a two-dimensional periodic array composed of cubic surface plasmon polariton nanostructures on a silicon carbide substrate in Embodiment 2 of the present application; and

(7) FIG. 6 illustrates a two-dimensional periodic array composed of cylindrical surface plasmon polariton nanostructures on the silicon carbide substrate in Embodiment 2 of the present application.

(8) In the drawings, 1: silicon carbide substrate; 2: interdigital electrode; and 3: nanoparticle.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) This application will be described in detail below with reference to embodiments to make the objectives, technical solutions, and advantages of this application clearer. Obviously, provided below are merely some embodiments of the present application, which are not intended to limit the application. Other embodiments obtained by those of the ordinary skill in the art based on the embodiments provided herein without paying any creative effort shall fall within the scope of the present application.

(10) FIG. 1 is a structural diagram of a metal-semiconductor-metal silicon carbide-based ultraviolet photodetector in the prior art.

Embodiment 1

(11) As shown in FIG. 2, a silicon carbide-based full-spectrum-responsive photodetector of the disclosure includes a silicon carbide substrate 1, where a silicon surface of the silicon carbide substrate 1 is provided with a plurality of metal counter electrodes 2 and a surface plasmon polariton nanostructure 3. The metal counter electrodes 2 are arranged on the silicon carbide substrate 1, and the surface plasmon polariton nanostructure 3 is arranged between the metal counter electrodes 2. The surface plasmon polariton nanostructure 3 includes a plurality of metal nanoparticles uniformly distributed on the silicon surface of the silicon carbide substrate 1. A Schottky contact is formed between the metal counter electrodes 2 and the silicon carbide substrate 1.

(12) In this embodiment, the silicon carbide substrate 1 is made of a semi-insulating 4H-SiC, and has an intrinsic carrier concentration of 1e13/cm.sup.3-1e15/cm.sup.3 and a thickness of 100-800 μm.

(13) In this embodiment, the plurality of metal counter electrodes 2 are made of gold, silver, titanium, nickel, palladium or cadmium.

(14) In this embodiment, the plurality of metal counter electrodes 2 are Cr/Pd double-layer electrodes or Ag/Ti double-layer electrodes.

(15) Further, in this embodiment, the surface plasmon polariton nanostructure is a randomly-distributed island-shaped metal nanoparticle structure 3 formed by annealing of a metal film; metal islands of the randomly-distributed island-shaped metal nanoparticle structure have an average diameter of 20-100 nm; and an average size of a gap between the metal islands is 50-300 nm.

(16) Further, in this embodiment, the interdigital electrodes 2 each have a finger width of 100-300 μm, a finger spacing of 100-300 μm, an effective area of 0.1 cm.sup.2 and 5-15 pairs of electrodes.

(17) This embodiment also provides a method of fabricating the silicon carbide-based full-spectrum-responsive photodetector, which includes the following steps.

(18) Firstly, a carbon surface and the silicon surface of the silicon carbide substrate 1 are calibrated through an atomic force microscope, where the silicon surface has a relatively low roughness. Then the silicon carbide substrate 1 is cleaned, dried, transferred to a magnetron sputtering coating chamber, and coated with a gold film with a thickness of 5 nm on the silicon surface by sputtering at a rate of 0.1 nm/s.

(19) The silicon carbide substrate 1 coated with a gold film is transferred to a muffle furnace, and the muffle furnace is heated to 500° C., and cooled to room temperature in an equal step manner within two hours to form island-shape gold nanoparticles. An interdigital electrode mask is loaded on the silicon carbide substrate 1 containing island-shaped golden nanoparticles, and an interdigital silver electrode with a thickness of 100 nm is deposited by evaporation at a rate of 0.1 nm/s, where the interdigital silver electrode has a finger width of 250 μm, a finger spacing of 250 μm, an effective area of 0.1 cm.sup.2 and 10 pairs of electrodes.

(20) The sample is taken out from the coating chamber, and the mask is removed to complete the preparation of the metal counter electrode 2, so that the silicon carbide-based ultraviolet-visible-near-infrared full-spectrum-responsive photodetector is obtained.

(21) The surface plasmon polariton nanostructure 3 of the photodetector prepared by the method of this embodiment is the island-shaped gold nanoparticle prepared by annealing, where the average diameter of the nano-island structure is 40 nm, and its SEM morphology is shown in FIG. 4A. FIG. 4B shows transient photocurrent response characteristics of the silicon carbide-based ultraviolet-visible-near-infrared full-spectrum-responsive photodetector in different wavebands, and it can be seen that the device exhibits electrical signal response to light of 375 nm, 660 nm, 850 nm, 1310 nm and 1550 nm under the bias of 0.1 V. Considering that the surface plasmon polariton resonance peak excited by the island-shaped gold nanoparticles contained in the device is in the visible light band, the current response of the device at wavelengths of 1310 nm and 1550 nm is relatively weak.

Embodiment 2

(22) This embodiment provides a silicon carbide-based full-spectrum-responsive photodetector. Similar to the Embodiment 1, the silicon carbide-based full-spectrum-responsive photodetector in this embodiment also includes a silicon carbide substrate 1; where a silicon surface of the silicon carbide substrate 1 is provided with a plurality of metal counter electrodes 2 and a surface plasmon polariton nanostructure 3. The metal counter electrodes 2 are arranged on the silicon carbide substrate 1, and the surface plasmon polariton nanostructure 3 is arranged between the metal counter electrodes 2. The surface plasmon polariton nanostructure 3 includes a plurality of metal nanoparticles uniformly distributed on the silicon surface of the silicon carbide substrate 1. A Schottky contact is formed between the metal counter electrodes 2 and the silicon carbide substrate 1.

(23) This embodiment is different from Embodiment 1 in the structure of the surface plasmon polariton nanostructure 3. As shown in FIGS. 5-6, in this embodiment, the surface plasmon polariton nanostructure 3 is an array structure formed by cubic nanostructures with a side length of 20-500 nm or cylindrical nanoparticles with a diameter of 20-500 nm with a period of 50-1000 nm, and the nanoparticles each have a height of 20-500 nm.

(24) In this embodiment, the nano-particle has a Cr/Au double-layer structure. The Au nanostructure layer can stimulate the surface plasmon polariton effect to effectively broaden the spectral absorption, and the Cr nanoparticle layer can not only enhance the adhesion between the Au film and the substrate, but also can adjust height of the Au/SiC Schottky barrier to some extent.

(25) In this embodiment, the metal counter electrode 2 is an interdigital electrode, which has a finger width of 100-300 μm, a finger spacing of 100-300 μm, an effective area of 0.1 cm.sup.2 and 5-15 pairs of electrodes.

(26) Further, this embodiment also provides a method of fabricating the silicon carbide-based full-spectrum-responsive photodetector, which includes the following steps.

(27) Firstly, the silicon carbide substrate 1 is cleaned and dried.

(28) Next, a polymethyl methacrylate (PMMA) photoresist film (with a thickness of 80 nm) is made on the silicon surface of the silicon carbide substrate through spin coating, and exposed by deep ultraviolet lithography or electron beam lithography, in which an exposure pattern is consistent with a pattern of the surface plasmon polariton nanostructure (a square array with length and width both of 50 nm; the periods of the row and column are both 300 nm; and 5000 units for each row and column). The silicon carbide substrate is immersed into a developer solution for fixing, rinsed and subjected to blow drying.

(29) Then, a Cr adhesion layer with a thickness of 5 nm and an Au film with a thickness of 50 nm are deposited on a surface of the silicon carbide substrate by magnetron sputtering, and the silicon carbide substrate is immersed in acetone to peel off unexposed PMMA photoresist and Cr and Au thereon, and subjected to blow drying to complete preparation of the surface plasmon polariton nanostructure.

(30) The metal counter electrode 2 is fabricated according to the preparation method of the surface plasmon polariton nanostructure 3, where the thickness of the PMMA film is 200 nm; the rectangular pattern with a length of 300 μm and a width of 30 μm is written on both sides of the surface plasmon polariton nanostructure 3 during the exposure. The two rectangles just sandwich all the surface plasmon polariton nanostructures 3. The 20 nm Cr/150 nm Pd composite film is deposited by magnetron sputtering. The metal counter electrode 2 is prepared after peeling off the unexposed PMMA to obtain the silicon carbide-based ultraviolet-visual-near-infrared full-spectrum-responsive photodetector.

(31) Finally, it should be noted that the embodiments described above are only used to illustrate the technical solutions, but not intended to limit the application. It should be understood that any modifications, replacements and variations made by those of ordinary skill in the art without departing from the spirit of the application should fall within the scope of the application defined by the appended claims.