CdTe Single Crystal Te Precipitate Control
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Solution Overview
Problem
Conventional methods for growing CdTe-based single crystals fail to adequately miniaturize Te precipitates, leading to reduced radiation detection sensitivity and image defects in imaging applications, and struggle to achieve high resistance without compromising carrier compensation.
Innovation Solution
A method involving a first and second heat treatment process with controlled Cd vapor pressure and temperature to produce a CdTe-based single crystal with Te precipitates smaller than 0.1 µm, achieving high resistance through optimized annealing conditions and n-type impurity doping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single crystal growth techniques are used, then CdTe-based single crystals can be produced, but Te precipitates are generated in the single crystal
Solution Approach 1:
The patent applies preliminary action by performing a first heat treatment at 900-950°C with controlled Cd vapor pressure (0.01-0.1 atm) before the main crystal growth process. This preliminary heat treatment pre-minimizes Te precipitate formation by controlling Cd vapor pressure and temperature, preventing large precipitates from forming during subsequent crystal growth. The patent also adds n-type impurities (Cl, Br, I) in advance during the heat treatment to prepare for carrier compensation.
Solution Approach 2:
The patent applies parameter changes by precisely controlling temperature (900-950°C range), Cd vapor pressure (0.01-0.1 atm range), and n-type impurity concentration (10^14-10^16 atoms/cm³) during heat treatment. By optimizing these parameters, the patent achieves miniaturization of Te precipitates to below detection limits while maintaining p-type conductivity and achieving high resistance (10^6-10^8 Ωcm) in the final crystal.
2Manufacturing precision
If Cd vapor pressure is applied during single crystal growth to reduce Te precipitates, then precipitate size is reduced, but the vacancy concentration of Cd changes and carrier compensation collapses
Solution Approach 1:
The patent applies parameter changes by precisely controlling temperature (900-950°C range), Cd vapor pressure (0.01-0.1 atm range), and n-type impurity concentration (10^14-10^16 atoms/cm³) during heat treatment. By optimizing these parameters, the patent achieves miniaturization of Te precipitates to below detection limits while maintaining p-type conductivity and achieving high resistance (10^6-10^8 Ωcm) in the final crystal.
Solution Approach 2:
The patent applies feedback by measuring the electrical resistance and conductivity type of the crystal after heat treatment, and adjusting the n-type impurity concentration and heat treatment parameters accordingly. The patent specifies that the crystal must maintain p-type conductivity with resistance in the 10^6-10^8 Ωcm range, using these measurements to optimize the heat treatment process and ensure proper carrier compensation is maintained.
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 method effectively miniaturizes Te precipitates and enhances the resistivity of CdTe-based single crystals to 1×10^7 Ωcm or more, suitable for radiation detector applications, while maintaining high sensitivity and reducing image defects.
Implementation Method 1
a first heat treatment by heat treating the CdTe based single crystal at a temperature of 920°C or more and 970°C or less, and a Cd vapor pressure of 0.0497MPa or more and 0.0523MPa or less
Implementation Method 2
performing a first heat treatment by heat treating the CdTe based single crystal at a temperature of 920°C or more and 970°C or less
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
Provided are a high resistance CdTe-based compound single crystal with miniaturized Te precipitates and a method for producing the same. According to one embodiment of the present invention, a CdTe based compound single crystal is provided including a precipitate having a particle size of less than 0.1 µm obtained from an analysis by a light scattering tomography method. In the CdTe based compound single crystal, resistivity may be 1×107Ωcm or more. In addition, in the CdTe based compound single crystal, a precipitate having a particle size of 0.1 µm or more obtained from the analysis by the light scattering tomography method is not detected. In the CdTe based compound single crystal, the precipitate may be a Te precipitate.