Ge-Bi-Te-M Recording Layer for High-Speed Phase Change Stability
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Solution Overview
Problem
Current phase-change type information recording media face challenges in achieving high crystallization speed and stability of the amorphous phase, especially at high linear velocities, leading to reliability issues and signal quality degradation.
Innovation Solution
A Ge-Bi-Te-M-based material with specific compositional formulas, including GeaBibTedM100-a-b-d and (GeTe)x[(M2Te3)y(Bi2Te3)100-x, is used in the recording layer, incorporating elements like Al, Ga, or In to enhance crystallization temperature and stability, allowing for high-speed recording and erasure across a wide range of linear velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the crystallization speed of the recording layer material is increased to enable high-speed recording (16× speed), then the recording speed is improved, but the stability of the amorphous phase deteriorates and signal quality degrades
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional ratios of Ge, Bi, Te, and M elements in the recording layer material, as well as controlling the thickness of the recording layer to 5-12 nm. These parameter adjustments enable the material to achieve both high crystallization speed for fast recording and sufficient amorphous phase stability for reliable signal storage
Solution Approach 2:
The patent uses composite materials by combining Ge-Bi-Te base material with additional M elements (such as In, Ga, or Al) to create a multi-component alloy system. This composite structure allows the material to exhibit both high crystallization speed and stable amorphous phase characteristics, resolving the contradiction between speed and reliability
2Speed
If the thickness of the recording layer is reduced to decrease heat capacity and improve cooling speed, then the crystallization speed is improved, but the material requires higher crystallization speed which may compromise amorphous phase stability
Solution Approach 1:
The patent applies parameter changes by optimizing both the thickness of the recording layer (5-12 nm) and the compositional parameters of the material simultaneously. This dual parameter optimization ensures that the thin layer provides fast cooling and crystallization while the specific material composition maintains amorphous phase stability even at high speeds
3Speed
If the proportion of SnTe is increased in Ge-Sn-Sb-Te material to achieve higher crystallization speed, then the crystallization speed is improved, but the material composition stability deteriorates due to phase separation
Solution Approach 1:
The patent uses composite materials by creating a Ge-Bi-Te-M system where Bi2Te3 and M2Te3 are combined with GeTe in specific proportions. This composite structure achieves high crystallization speed while preventing phase separation through the synergistic interaction of multiple components, maintaining compositional stability during repeated recording operations
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 solution provides a recording medium with high erasability and excellent archival characteristics, ensuring reliable signal stability at both high and low linear velocities, and across varying recording densities and wavelengths.
Implementation Method 1
a recording layer (104) which can generate a reversible phase change between an amorphous phase and a crystalline phase
Implementation Method 2
information is recorded, erased and overwritten using a reversible phase change between an amorphous phase (recording) and a crystalline phase (erasing)
Data Source
AI summary
In an information recording medium on and from which information is recorded and reproduced by applying light or electric energy, a recording layer which generates reversible phase change is formed so as to include a material containing Ge, Bi, Te and an element “M” which material is expressed with (GeTe)x[(M2Te3)y(Bi2Te3)1-y]100-x (mol %) wherein “M” represents at least one element selected from Al, Ga and In, and “x” and “y” satisfy 80≦x<100 and 0<y≦0.9, whereby the medium is obtained which ensures a high erasability and an excellent archival characteristic at a high linear velocity and in a wide range of linear velocities.