Apparatus and methods for probing a material as a function of depth using depth-dependent second harmonic generation

Patent metadata

Field	Value
Publication number	US-10371668-B2
Application number	US-201515324100-A
Country	US
Kind code	B2
Filing date	Jul 13, 2015
Priority date	Jul 11, 2014
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A method for non-invasively probing at least one physics property of a solid material. In one embodiment, the method has the steps of splitting a photon beam into a first photon beam and a second photon beam, exposing the solid material to the first photon beam to generate a coherent acoustic phonon wave in the solid material at time t, and exposing the solid material to the second photon beam at a time t+Δt, where t+Δt≥t, to generate corresponding second harmonic generation signals, where from the corresponding second harmonic generation signals, the at least one physics property of the solid material is determinable.

First claim

What is claimed is:

1. A method for non-invasively probing at least one physics property of a solid material, wherein the solid material is in a form of a solid material layer having a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, wherein a layered structure is formed with a transducing layer deposited on the solid material layer, and wherein as formed, the layered structure has a first surface that is a surface of the transducing layer, a second, opposite surface that is a surface of the solid material layer, and an interface therebetween, comprising the steps of:
(a) splitting a photon beam into a first photon beam and a second photon beam, wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the photon beam;
(b) exposing the first surface of the layered structure to the first photon beam at time t with a first incident angle α 1 to induce a coherent acoustic phonon wave in the transducing layer, which travels into the body portion of the solid material layer with a moving surface;
(c) exposing the first surface of the layered structure to the second photon beam at time t+Δt, where t+Δt≥t, with a second incident angle α 2 to produce a reflection beam comprising a first reflection beam and a second reflection beam, respectively, such that the first reflection beam comprises a first portion of the second photon beam that is reflected from the first surface of the layered structure, and the second reflection beam comprises a second portion of the second photon beam that is reflected from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material layer at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
(d) spatially separating the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam;
(e) detecting the second harmonic generation signals;
(f) measuring intensities of the second harmonic generation signals; and
(g) determining the at least one physics property of the solid material at or around the depth h from the measured second harmonic generation intensities.

2. The method of claim 1 , wherein the photon beam comprises substantially monochromatic electromagnetic radiation.

3. The method of claim 2 , wherein the substantially monochromatic electromagnetic radiation comprises a laser beam.

4. The method of claim 3 , wherein the laser beam comprises a pulsed laser beam.

5. The method of claim 1 , wherein the solid material layer has at least one physics property same or different from that of the transducing layer.

6. The method of claim 1 , wherein the body portion of the solid material layer has a thickness H 2 .

7. The method of claim 6 , wherein the solid material is one of a semiconductor material, a metallic material, an insulator material, and a dielectric material.

8. The method of claim 6 , wherein the solid material is one of GaAs, GaSb, GaSb/GaAs, Si, SiO 2 /Si and silicon on insulator (SOI).

9. The method of claim 6 , wherein the transducing layer has a thickness H 1 .

10. The method of claim 9 , wherein the thickness H 1 and the thickness H 2 satisfying the relationship of H 2 /H 1 >1.

11. The method of claim 10 , wherein the transducing layer is formed from GaSb, the solid material is GaAs, the thickness H 1 is in the range of 10-30 nm, and the thickness H 2 is in the range of 50-1000 nm.

12. The method of claim 1 , wherein the transducing layer is formed from one of a semiconductor material, a metallic material, an insulator material, and a dielectric material.

13. The method of claim 12 , wherein the transducing layer is formed from one of GaAs, GaSb, GaSb/GaAs, Si, SiO 2 /Si and silicon on insulator (SOI).

14. The method of claim 1 , wherein the interface is one of a semiconductor/dielectric interface, a semiconductor/semiconductor interface, a metal/insulator interface, and a metal/dielectric interface.

15. The method of claim 1 , wherein the first incident angle α 1 is the angle between the first photon beam and an axis perpendicular to the first surface of the layered structure, and satisfies the relationship of: 0≤α 1 <90°.

16. The method of claim 15 , wherein the second incident angle α 2 is the angle between the second photon beam and the axis perpendicular to the first surface of the layered structure, and satisfies the relationship of: 0<α 2 <90°.

17. The method of claim 1 , wherein the measuring step comprises the step of detecting the second harmonic generation signals by a photomultiplier tube.

18. The method of claim 17 , wherein the measuring step is performed with a photon counter.

19. The method of claim 1 , wherein the at least one physics property of the solid material comprises at least one of defect, defect concentration, defect sensitivity, type of defect, spatial resolution, electronic structure, lattice, lattice mismatch, lattice disorder, dopants, impurities, interface(s), interfacial strain, interface roughness, interface state density, trapped charge density, surface recombination velocity, electrically active impurity, and interface morphology.

20. A method for non-invasively probing at least one physics property of a solid material, wherein the solid material is in a form of a solid material layer having a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, comprising the steps of:
(a) splitting a photon beam into a first photon beam and a second photon beam, wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the photon beam;
(b) with the first photon beam, generating a coherent acoustic phonon wave to travel in the body portion of the solid material with a moving surface at time t;
(c) with the second photon beam, producing a reflection beam comprising a first reflection beam and a second reflection beam, respectively, such that the first reflection beam comprises a first portion of the second photon beam that is not reflected from the coherent acoustic phonon wave, and the second reflection beam comprises a second portion of the second photon beam that is reflected, at a time t+Δt, where t+Δt≥t, from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material layer at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
(d) spatially separating the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam; and
(e) measuring intensities of the corresponding second harmonic generation signals, from which the at least one physics property of the solid material at or around the depth h is determinable.

Assignees

• Univ Vanderbilt

Inventors

• Garnett Joy
• Krzyzanowska Halina
• Tolk Norman H

Classifications

• G01N2021/8477

  Investigating crystals, e.g. liquid crystals · CPC title

• G01N29/2418 Primary

  using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics (photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046) · CPC title

• G01N2021/8438

  Mutilayers · CPC title

• G01N29/043

  in the interior, e.g. by shear waves · CPC title

• G01N21/9505

  Wafer internal defects, e.g. microcracks · CPC title