Hydrogen-free amorphous dielectric insulating thin films with no tunneling states

Patent metadata

Field	Value
Publication number	US-9530535-B2
Application number	US-201414538968-A
Country	US
Kind code	B2
Filing date	Nov 12, 2014
Priority date	Nov 13, 2013
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

A hydrogen-free amorphous dielectric insulating film having a high material density and a low density of tunneling states is provided. The film is prepared by e-beam deposition of a dielectric material on a substrate having a high substrate temperature T sub under high vacuum and at a low deposition rate. In an exemplary embodiment, the film is amorphous silicon having a density greater than about 2.18 g/cm 3 and a hydrogen content of less than about 0.1%, prepared by e-beam deposition at a rate of about 0.1 nm/sec on a substrate having T sub =400° C. under a vacuum pressure of 1×10 −8 Torr.

First claim

What is claimed is:

1. A process for making a high-density amorphous silicon dielectric insulating thin film having no two-level tunneling states (TLS) for a superconducting circuit, comprising:
depositing hydrogen-free amorphous silicon on a substrate having a substrate temperature T sub between about 350° and 400° C. the hydrogen-free amorphous silicon being deposited under a high vacuum pressure between about 1×10 −7 and about 1×10 −11 Torr and at a deposition rate of less than 0.1 nm/sec;
wherein the substrate temperature, vacuum pressure, and deposition rate are configured to cause the hydrogen-free amorphous silicon to not become crystalline but to remain in its amorphous state to form a TLS-free amorphous silicon dielectric insulating thin film having a density of at least about 2.18 g/cm 3 .

2. The process according to claim 1 , wherein the hydrogen-free silicon is deposited on the substrate by electron beam evaporation, sputtering, or pulsed laser deposition.

3. A product made by the process of claim 1 .

4. A process for preparing a high-density amorphous silicon dielectric insulating thin film having no two-level tunneling state (TLS) for a superconducting circuit, comprising:
depositing hydrogen-free amorphous silicon on a substrate having a substrate temperature T sub between about 350° C. and about 400° C. by electron beam evaporation under a pressure of about 1×10 −8 Torr and at a deposition rate of less than 0.1 nm/sec;
wherein the substrate temperature, vacuum pressure, and deposition rate are configured to cause the hydrogen-free amorphous silicon to not become crystalline but to remain in its amorphous state to form a TLS-free amorphous silicon dielectric insulating thin film having a density of at least about 2.18 g/cm 3 .

5. A product made by the process of claim 4 .

6. A method for making a Josephson junction with a high-density amorphous silicon dielectric insulating thin film having no two-level tunneling states (TLS), comprising:
depositing a first superconducting material layer on a substrate;
depositing hydrogen-free amorphous silicon on the first superconducting material layer, the hydrogen-free amorphous silicon being deposited with a substrate temperature between 350° and 400° C. under a high vacuum pressure between about 1×10 −7 and about 1×10 −11 Torr and at a deposition rate of about 0.1 nm/sec; and
depositing a second superconducting material layer on the amorphous silicon dielectric insulating thin film;
wherein the substrate temperature, vacuum pressure, and deposition rate are configured to cause the hydrogen-free amorphous silicon to not become crystalline but to remain in its amorphous state to form a TLS-free amorphous silicon thin film having a density of at least about 2.18 g/cm 3 ;
wherein the amorphous silicon thin film comprises an insulating dielectric layer separating the first and second superconducting material layers.

7. The process according to claim 6 , wherein the hydrogen-free silicon is deposited on the substrate by electron beam evaporation, sputtering, or pulsed laser deposition.

8. A product made by the process of claim 6 .

Assignees

• Us Navy

Inventors

• Liu Xiao
• Queen Daniel R
• Hellman Frances

Classifications

• H10P14/6332

  using thermal evaporation (formation of epitaxial layers by a deposition process H10P14/6349) · CPC title

• H10P14/6326

  Deposition processes · CPC title

• H10P14/60

  of insulating materials · CPC title

• C21D1/40

  Direct resistance heating · CPC title

• C21D1/773

  under reduced pressure or vacuum · CPC title