Laser-Assisted Crystal Growth for Large-Diameter Rods
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Solution Overview
Problem
Current optical floating zone furnaces are unable to grow large-size crystals due to uneven heating and incomplete core melting of test rods with diameters greater than 15 mm, leading to unstable floating molten zones and ineffective crystal growth.
Innovation Solution
A laser-assisted heating method combined with a dedicated device that uses a xenon lamp for surface heating and a laser for core heating, providing a highly precise and controllable heat source to stabilize the floating molten zone and achieve uniform heating, allowing for the growth of crystals with diameters ≥30 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional optical floating zone furnace with xenon lamps is used for heating, then the surface of the test rod can be heated, but the core of large-diameter test rods (>15 mm) cannot be completely melted due to uneven heating
Solution Approach 1:
The heating system is segmented into two independent heating sources: xenon lamps for surface heating and laser for core heating. This segmentation allows each heating source to target specific regions of the test rod, solving the problem of uneven heating in large-diameter rods where surface heating alone cannot adequately heat the core.
Solution Approach 2:
Different heating methods are applied to different parts of the test rod: xenon lamps provide surface heating while laser provides core heating. This local quality approach ensures that each region of the test rod receives the appropriate heating intensity and distribution, achieving complete and uniform melting throughout the entire cross-section.
2Volume of moving object
If the test rod diameter is increased to grow large-size crystals, then the crystal size can be increased, but the floating molten zone becomes unstable due to incomplete core melting
Solution Approach 1:
Two heating systems (xenon lamps and laser) are merged into a single integrated heating system. The xenon lamps provide surface heating while the laser provides core heating, and both work simultaneously to achieve complete melting and stable molten zone formation in large-diameter test rods, enabling growth of large-size crystals with diameters ≥30 mm.
3Device complexity
If only surface heating by xenon lamp is used, then the device structure can be simple, but large-size crystals cannot be grown due to insufficient core heating
Solution Approach 1:
The heating system is designed with multi-functionality to handle different crystal growth requirements. The xenon lamps provide general surface heating for all operations, while the laser provides supplemental core heating specifically for large-diameter test rods. This universal design allows the same device to grow crystals of various sizes, from small to large (≥30 mm), without requiring different equipment.
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 enables the successful growth of large-sized crystals with enhanced temperature gradients and improved solid-liquid interface stability, increasing the success rate of seeding and producing high-quality crystals with diameters up to 35 mm.
Implementation Method 1
a laser beam is introduced to a center portion of the floating molten zone to perform surface heating by the xenon lamp and core heating by the laser as a composite heating method
Implementation Method 2
the focal point of the xenon light sources are focused a surface of a test rod after focusing by the ellipsoidal mirrors, the test rod is gradually heated up from the surface thereof by means of thermal conductive
Implementation Method 3
the test rod is gradually heated up from the surface thereof by means of thermal conductive in order to melt the test rod
Implementation Method 4
the floating molten zone is formed between the feed rod and the seed crystal rod
Data Source
AI summary
The object of the present invention is to provide a method for growing a large-size crystal by laser assisted heating and a dedicated device. The device comprises a laser core heating device, a xenon lamp surface heating device, a base, a vacuum cavity and etc. When a crystal is prepared, seeding and crystal growing are implemented by a xenon lamp-laser synergetic heating mode. According to the present invention, the structure and functions of the dedicated device are designed to introduce, at the center of a float melting zone, a laser heating source having high precision and strong controllability, so that a composite heating mode with xenon lamp surface heating and laser core heating is formed; and combined with the control of process, the method and the device solve the difficulty in growing a large-size test crystal bar and enable the growth of the crystal bar having a diameter up to 35 mm so as to facilitate engineering uses.