InP Single Crystal Substrate Cooling for High Zn Activation
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Solution Overview
Problem
The existing methods for producing Zn-doped InP single crystal substrates face challenges in achieving high electrical activation ratios and uniformity, particularly in highly doped regions with Zn concentrations above 5 × 10^18 cm^-3, leading to decreased carrier density and increased dislocation density, which affects the production yield and device performance.
Innovation Solution
A method involving the rapid cooling of InP single crystal ingots from 1020 °C to 820 °C within 2 to 7.5 minutes, using a thermal baffle to control the temperature gradient and prevent contact with the baffle during cooling, while rotating the ingot at 1-5 rpm, results in a Zn-doped InP single crystal substrate with an electrical activation ratio of over 85% and reduced dislocation density, ensuring uniform characteristics across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Zn is doped at high concentration (>5×10^18 cm^-3) to increase carrier density, then electrical conductivity is improved, but electrical activation ratio decreases and dislocation density increases
Solution Approach 1:
The invention changes the cooling rate parameter from conventional slow cooling to rapid cooling (10-30°C/min) during the solidification process. This parameter change enables the formation of highly doped InP single crystals with Zn concentration >5×10^18 cm^-3 while maintaining electrical activation ratio >80% and dislocation density <500 cm^-2, effectively resolving the contradiction between high carrier density and low activation ratio
Solution Approach 2:
The invention performs preliminary rapid cooling treatment immediately after crystal growth before the crystal is removed from the furnace. This preliminary action of rapid cooling (completing within 1-5 minutes) prevents subsequent slow cooling that would cause dislocation formation and activation ratio decrease, thereby maintaining high electrical activation ratio and low dislocation density in highly doped regions
2Reliability
If conventional cooling rate is used after crystal growth, then crystal structure is maintained, but electrical activation ratio decreases and dislocation density increases
Solution Approach 1:
The invention changes the cooling rate parameter from conventional slow cooling to rapid cooling (10-30°C/min) during the solidification process. This parameter change enables the formation of highly doped InP single crystals with Zn concentration >5×10^18 cm^-3 while maintaining electrical activation ratio >80% and dislocation density <500 cm^-2, effectively resolving the contradiction between high carrier density and low activation ratio
Solution Approach 2:
The invention performs preliminary rapid cooling treatment immediately after crystal growth before the crystal is removed from the furnace. This preliminary action of rapid cooling (completing within 1-5 minutes) prevents subsequent slow cooling that would cause dislocation formation and activation ratio decrease, thereby maintaining high electrical activation ratio and low dislocation density in highly doped regions
3Stability of the object's composition
If slow cooling is used to maintain crystal structure, then crystal integrity is preserved, but dislocation density increases and productivity decreases
Solution Approach 1:
The invention changes the cooling rate parameter from conventional slow cooling to rapid cooling (10-30°C/min) during the solidification process. This parameter change enables the formation of highly doped InP single crystals with Zn concentration >5×10^18 cm^-3 while maintaining electrical activation ratio >80% and dislocation density <500 cm^-2, effectively resolving the contradiction between high carrier density and low activation ratio
Solution Approach 2:
The invention performs preliminary rapid cooling treatment immediately after crystal growth before the crystal is removed from the furnace. This preliminary action of rapid cooling (completing within 1-5 minutes) prevents subsequent slow cooling that would cause dislocation formation and activation ratio decrease, thereby maintaining high electrical activation ratio and low dislocation density in highly doped regions
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 achieves a high electrical activation ratio of Zn (>85%) and low dislocation density (<500 cm^-2) across the substrate, enhancing production yield and enabling the design of devices with uniform characteristics, thereby improving production efficiency and reducing costs.
Implementation Method 1
using a thermal baffle to control the temperature gradient and prevent contact with the baffle during cooling
Implementation Method 2
rapid cooling of InP single crystal ingots from 1020 °C to 820 °C within 2 to 7.5 minutes
Implementation Method 3
rotating the ingot at 1-5 rpm
Data Source
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AI summary
Provided is a large diameter InP single crystal substrate having a diameter of 75 mm or more, which can achieve a high electrical activation rate of Zn over a main surface of the substrate even in a highly doped region having a Zn concentration of 5 × 1018 cm-3 or more; and a method for producing the same. An InP single crystal ingot is cooled such that a temperature difference of 200 °C is decreased for 2 to 7.5 minutes, while rotating the InP single crystal ingot at a rotation speed of 10 rpm or less, and the cooled InP single crystal ingot is cut into a thin plate, thereby allowing production of the InP single crystal substrate having an electrical activation rate of Zn of more than 85% over the main surface of the substrate even in a highly doped region having a Zn concentration of 5 × 1018 cm-3 or more.