CPP-GMR Device with Doped ZnO Spacer Layer
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Solution Overview
Problem
Current magnetoresistive devices face challenges in achieving high MR ratios while maintaining low area resistivity, particularly in reducing device size and ensuring reliability, as previous solutions like the CPP-GMR device have limited improvements in MR ratio and are prone to characteristic variations.
Innovation Solution
A CPP-GMR device with a spacer layer comprising zinc oxide doped with metal elements like Zn, Ge, or Cr, sandwiched between two ferromagnetic layers, where the semiconductor oxide layer is formed using the MBE technique, allowing for precise control of dopant concentration and thickness to optimize electrical conductivity and MR ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CPP-GMR device uses a nonmagnetic metal intermediate layer to achieve high MR ratio, then the MR ratio improves, but the area resistivity increases and device size reduction becomes difficult
Solution Approach 1:
The patent changes the material parameter of the spacer layer from conventional nonmagnetic metal to doped semiconductor oxide (ZnO doped with Ge, V, or Cr). This material parameter change enables achieving high MR ratio (15% or more) while maintaining low area resistivity (0.05 to 0.5 Ω·μm²), thus allowing device area reduction without sacrificing MR performance
Solution Approach 2:
The patent uses composite material structure by doping metal elements (Ge, V, Cr) into ZnO semiconductor oxide to create a spacer layer with optimized electrical properties. This composite approach achieves both high MR ratio and low area resistivity simultaneously, resolving the contradiction between MR ratio improvement and device size reduction
2Measurement precision
If Cu-pillar is used for current narrowing to increase MR ratio, then MR ratio improves, but manufacturing precision becomes difficult to maintain
Solution Approach 1:
The patent extracts and eliminates the Cu-pillar component from the device structure entirely. By using doped semiconductor oxide as the spacer layer, the invention removes the need for Cu-pillar current narrowing structures, thereby eliminating the manufacturing precision issues associated with Cu-pillar positioning while still achieving high MR ratio through material property optimization
3Area of stationary object
If doped semiconductor oxide layer is used to reduce area resistivity, then area resistivity decreases, but noise increases due to shot noise
Solution Approach 1:
The patent optimizes the doping concentration parameter of metal elements in ZnO to achieve the carrier concentration range of 10¹⁹ to 10²¹ carriers/cm³. This parameter optimization balances area resistivity reduction with shot noise suppression, achieving low area resistivity (0.05 to 0.5 Ω·μm²) while maintaining acceptable noise levels through controlled carrier density
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution achieves high MR ratios while maintaining low area resistivity, reducing noise, and enhancing device reliability by optimizing the dopant concentration and thickness of the semiconductor oxide layer, thereby improving the performance of magnetoresistive devices.
Implementation Method 1
said semiconductor oxide layer forming a part of said spacer layer is zinc oxide of wurtzite structure, and said zinc oxide is doped with a dopant comprising at least one metal element selected from the group consisting of zinc or Zn, germanium or Ge, vanadium or V, and chromium or Cr
Implementation Method 2
a giant magnetoresistive device (CPP-GMR device) of a CPP (current perpendicular to plane) structure, comprising a spacer layer, and two ferromagnetic layers stacked together and formed while said spacer layer is sandwiched between them
Data Source
AI summary
The semiconductor oxide layer that forms a part of the spacer layer in the inventive giant magnetoresistive device (CPP-GMR device) is composed of zinc oxide of wurtzite structure that is doped with a dopant given by at least one metal element selected from the group consisting of Zn, Ge, V, and Cr in a content of 0.05 to 0.90 at %: there is the advantage obtained that ever higher MR ratios are achievable while holding back an increase in the area resistivity AR.