JP-7855856-B2 - Nitride semiconductor material and thermal flow switching element equipped therewith

JP7855856B2JP 7855856 B2JP7855856 B2JP 7855856B2JP-7855856-B2

Inventors

藤田利晃
安達真樹

Assignees

三菱マテリアル株式会社

Dates

Publication Date: 20260511
Application Date: 20211220
Priority Date: 20210226

Claims (4)

It is a metal nitride represented by M-Si-N-Te (where M represents at least one transition metal element and Te is an arbitrary element), and is a nanocrystal. A nitride semiconductor material characterized in that M is at least one of Cr, Mn, Ni, and Mo.
In the nitride semiconductor material according to claim 1, A nitride semiconductor material characterized in that the metal nitride is represented as M-Si-N (where M is at least one of Cr, Mn, Ni, and Mo).
In the nitride semiconductor material according to claim 2, A nitride semiconductor material characterized by its use as a low thermal conductivity material with a thermal osmotic pressure of less than 2000 Ws 0.5 / m² K.
N-type semiconductor layer, An insulating layer stacked on the aforementioned N-type semiconductor layer, The insulator layer comprises a P-type semiconductor layer laminated on the aforementioned insulating layer, A thermal flow switching element characterized in that at least one of the N-type semiconductor layer and the P-type semiconductor layer is formed of a nitride semiconductor material according to any one of claims 1 to 3.

Description

This invention relates to a nitride semiconductor material having low lattice thermal conductivity and a heat flow switching element equipped therewith. Conventionally, as a heat flow switch that actively changes thermal conductivity by bias voltage, for example, Non-Patent Document 1 proposes a heat flow switching element that changes thermal conductivity by sandwiching an electrically insulating polyimide tape between two semiconductor materials: Ag₂S₀.6Se₀.4 and applying an electric field. Takuya Matsunaga, et al., "Fabrication of a Heat Flow Switching Element Operated by Bias Voltage," The 15th Annual Conference of the Thermoelectric Society of Japan, September 13, 2018. This is a perspective view showing one embodiment of the nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention.This embodiment is a conceptual diagram for explaining the principle.This is a cross-sectional SEM image showing a comparative example of a nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention.This is a cross-sectional SEM image showing an embodiment of the nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention.This is a cross-sectional TEM image showing an embodiment of the nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention.This is a cross-sectional TEM image showing an embodiment of the nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention. Hereinafter, an embodiment of the nitride semiconductor material and a thermal flow switching element equipped therewith according to the present invention will be described with reference to Figures 1 and 2. Note that the scale of the drawings used in the following description has been appropriately changed as needed to make each part recognizable or easily recognizable. As shown in Figures 1 and 2, the heat flow switching element 1 of this embodiment comprises an N-type semiconductor layer 3, an insulating layer 4 laminated on the N-type semiconductor layer 3, and a P-type semiconductor layer 5 laminated on the insulating layer 4. Furthermore, the heat flow switching element 1 of this embodiment includes an N-side electrode 6 connected to an N-type semiconductor layer 3 and a P-side electrode 7 connected to a P-type semiconductor layer 5. The above-mentioned N-type semiconductor layer 3 and P-type semiconductor layer 5 are nitride semiconductor materials with low thermal conductivity, and are metal nitrides represented by M-Si-N-Te (where M represents at least one transition metal element and Te is an arbitrary element), and are nanocrystals. Furthermore, the above nitride semiconductor material has a thermal osmotic coefficient of less than 2000 Ws /0.5 / m²K and an electrical resistivity of less than 10 Ωcm. In this specification, materials with a crystal size of 5 nm or less are referred to as nanocrystals, including amorphous materials. Furthermore, the crystal size mentioned above was determined by randomly selecting 10 crystals from the cross-sectional TEM image and calculating the average of their equivalent circle diameters. The above M is at least one of Cr, Mn, Ni, Mo, and W. In other words, the above metal nitrides include Cr-Si-N, Mn-Si-N, Ni-Si-N, Mo-Si-N, W-Si-N, Cr-W-Si-N, Cr-Si-N-Te, W-Si-N-Te, and so on. These film deposition methods employ various techniques, such as sputtering and molecular beam epitaxy (MBE). Regarding the sputtering method, the above-mentioned metal nitride can be deposited in a sputtering apparatus using targets with various composition ratios, under a mixed gas atmosphere of Ar gas and nitrogen gas, by varying the sputtering gas pressure, nitrogen gas partial pressure, etc. Furthermore, it is acceptable for the film to contain trace amounts of oxygen (O) as an unavoidable impurity during film formation. Furthermore, if voltage can be applied directly to the N-type semiconductor layer 3 and the P-type semiconductor layer 5, the N-side electrode 6 and the P-side electrode 7 are unnecessary. Furthermore, the heat flow switching element 1 of this embodiment comprises an insulating substrate 2, on which the N-side electrode 6 is formed. That is, the N-side electrode 6, N-type semiconductor layer 3, insulating layer 4, P-type semiconductor layer 5, and P-side electrode 7 are laminated on the substrate 2 in this order. Note that the layers may be laminated on the substrate 2 in the reverse order. Also, the substrate 2 itself may be the P-side electrode 7 or the N-side electrode 6. An external power supply V is connected to the N-side electrode 6 and P-side electrode 7, and a voltage is applied. The arrows in Figure 1 indicate the direction of voltage (electric field) application. The N-type semiconductor layer 3 and th