CdZnTe Crystal Uniformity via Controlled Thermal Processing
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Solution Overview
Problem
CdZnTe crystals exhibit varying carrier mobility lifetime products due to sensitive processing conditions, leading to inconsistent crystal characteristics and low yield, as even slight differences in processing can result in significant differences in crystal properties, making it challenging to achieve a high mobility lifetime product across a wide range of the crystal surface.
Innovation Solution
Controlled heat treatment after crystal growth, specifically maintaining a temperature difference of 20°C or less between the maximum and minimum temperatures during heat treatment at 800°C to 1000°C, combined with the vertical temperature gradient freeze method for growing the CdZnTe crystal ingot, ensures a high mobility lifetime product across a larger area of the crystal surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crystal growth methods are used without strict temperature control, then processing is simpler and more flexible, but the mobility lifetime product varies significantly across different regions of the crystal surface, resulting in low yield
Solution Approach 1:
The patent applies parameter changes by strictly controlling the temperature parameter during crystal growth. Specifically, it maintains the temperature difference between the maximum and minimum temperatures at 20°C or less, and controls the temperature within 800°C to 1000°C. This precise parameter control ensures uniform mobility lifetime product across the crystal surface while managing the complexity through defined temperature ranges.
Solution Approach 2:
The patent implements equipotentiality by minimizing temperature gradients across the crystal growth zone. By maintaining a temperature difference of 20°C or less between maximum and minimum temperatures, the system creates a nearly uniform thermal field that prevents regional variations in crystal characteristics, ensuring consistent mobility lifetime product across the entire crystal surface.
2Productivity
If heat treatment temperature is not strictly controlled, then the processing is more flexible and easier to operate, but the ratio of regions with high mobility lifetime product decreases, leading to lower production efficiency
Solution Approach 1:
The patent applies parameter changes by defining specific temperature ranges and tolerances for heat treatment. It controls the heat treatment temperature within 800°C to 1000°C and maintains the temperature difference at 20°C or less. This precise parameter specification increases the ratio of regions with high mobility lifetime product, thereby improving production efficiency while managing the precision requirement through clear temperature boundaries.
3Manufacturing precision
If the temperature difference during heat treatment is large, then the processing time can be reduced and productivity increased, but the mobility lifetime product becomes inconsistent across different crystal regions
Solution Approach 1:
The patent resolves this contradiction by optimizing the temperature parameter within a narrow range. By maintaining the temperature difference at 20°C or less and controlling the temperature between 800°C to 1000°C, it achieves consistent mobility lifetime product across crystal regions. The defined temperature parameters allow for efficient processing while ensuring uniformity, balancing precision requirements with time efficiency.
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
This approach significantly increases the ratio of regions with high mobility lifetime products on the same crystal surface, improving production efficiency and yield of CdZnTe single crystal substrates, thereby reducing product costs and enhancing device performance.
Implementation Method 1
heating the grown cadmium zinc telluride crystal ingot as an ingot; and cutting out a single crystal from the heated cadmium zinc telluride crystal ingot
Implementation Method 2
a temperature of the heating is 800° C. or higher and 1000° C. or lower, and wherein a difference between a maximum temperature and a minimum temperature in a region between an upper end portion and a lower end portion of the single crystal ingot is within 20° C.
Implementation Method 3
growing a cadmium zinc telluride crystal ingot
Implementation Method 4
the vertical temperature gradient freeze method for growing the CdZnTe crystal ingot
Data Source
AI summary
Provided is a cadmium zinc telluride (CdZnTe) single crystal including a main surface that has a high mobility lifetime product (μτ product) in a wide range, wherein the main surface has an area of 100 mm2 or more and has 50% or more of regions where the μτ product is 1.0×10−3 cm2/V or more based on the entire main surface, and a method for effectively producing the same.