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Spin polarized electron source

Foreign code F120006260
File No. J1018-02WO
Posted date Feb 21, 2012
Country EPO
Application number 09724694
Gazette No. 2270832
Gazette No. 2270832
Date of filing Mar 24, 2009
Gazette Date Jan 5, 2011
Gazette Date Feb 10, 2016
International application number JP2009001304
International publication number WO2009119074
Date of international filing Mar 24, 2009
Date of international publication Oct 1, 2009
Priority data
  • 2009JP001304 (Mar 24, 2009) WO
  • P2008-079292 (Mar 25, 2008) JP
Title Spin polarized electron source
Abstract To provide implement a spin-polarized electron generating device having high spin polarization and high external quantum efficiency while allowing a certain degree of freedom in selecting materials of a substrate, a buffer layer, and a strained superlattice layer.
In a spin-polarized electron generating device having a substrate, a buffer layer, and a strained superlattice layer formed on the buffer layer, an intermediate layer formed of a crystal having a lattice constant greater than that of a crystal used to form the buffer layer intervenes between the substrate and the buffer layer.
With this arrangement, tensile strain causes cracks to be formed in the buffer layer in a direction perpendicular to the substrate, whereby the buffer layer has mosaic-like appearance.
As a result, glide dislocations in an oblique direction do not propagate to the strained superlattice layer to be grown on the buffer layer, thereby improving crystallinity of the strained superlattice layer.
Accordingly, spin polarization of excited electrons and external quantum efficiency of polarized electrons improve.
Scope of claims [claim1]
1. A spin-polarized electron generating device comprising a substrate (10-12), a buffer layer (30-32), and a strained superlattice layer (40-42) formed on the buffer layer, wherein an intermediate layer (20-22) formed of a crystal having a lattice constant greater than that of a crystal of the buffer layer is disposed between the substrate and the buffer layer, characterized in that the buffer layer (30-32) has cracks formed therein in a direction perpendicular to the substrate (10-12) by the effect of tensile strain.
[claim2]
2. A spin-polarized electron generating device according to claim 1, wherein the substrate is formed of GaP; the buffer layer is formed of any one selected from a group consisting of GaAs xP 1-x (0 <= x <= 1), Ga yIn 1-yP (0 <= y <= 1), and Ga zIn 1-zAs (0 <= z <= 1); and the intermediate layer is formed of a binary, ternary, quaternary, or quinary compound AlGaInAsP having a lattice constant greater than that of the buffer layer.
[claim3]
3. A spin-polarized electron generating device according to claim 2, wherein the intermediate layer is formed of GaAs.
[claim4]
4. A spin-polarized electron generating device according to claim 1, wherein the substrate is formed of GaAs; the buffer layer is formed of any one selected from a group consisting of GaAs xP 1-x (0 <= x <= 1), Ga yIn 1-yP (0 <= y <= 1), and Ga zIn 1-zAs (0 <= z <= 1); and the intermediate layer is formed of a binary, ternary, quaternary, or quinary compound AlGaInAsP having a lattice constant greater than that of the buffer layer.
[claim5]
5. A spin-polarized electron generating device according to claim 4, wherein the intermediate layer is formed of InAs.
[claim6]
6. A spin-polarized electron generating device according to claim 1, wherein the substrate is formed of GaN; the buffer layer is formed of any one selected from a group consisting of Al xGa 1-xN (0 <= x <= 1) and Ga yIn 1-yN (0 <= y <= 1); and the intermediate layer is formed of a binary, ternary, or quaternary compound AlGaInN having a lattice constant greater than that of the buffer layer.
[claim7]
7. A spin-polarized electron generating device according to claim 6, wherein the intermediate layer is formed of InN.
[claim8]
8. A spin-polarized electron generating apparatus (100) comprising a spin-polarized electron generating device according to any one of claims 1 to 7.
[claim9]
9. A spin-polarized electron generating apparatus according to claim 8, wherein the spin-polarized electron generating apparatus is an electron microscope.
  • Applicant
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • Inventor
  • UJIHARA TORU
  • JIN XIUGUANG
  • TAKEDA YOSHIKAZU
  • NAKANISHI TSUTOMU
  • YAMAMOTO NAOTO
  • SAKA TAKASHI
  • KATOU TOSHIHIRO
IPC(International Patent Classification)
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