The 1 kW and 2 kW laser furnace for single crystal fabrication is based on a design and developed in close cooperation with the RIKEN Center for Emergent Matter Science under the leadership of Yoshio Kaneko. Both melting zones have 5 lasers each, which guarantees a high uniformity of power density in the melting zone range. The laser profile has been optimized to reduce thermal stress during the crystal growth process. In addition, the system includes an integrated temperature sensor for real-time temperature monitoring. Temperatures up to 3000 °C can be reached and therefore materials with a very high vapor pressure, a narrow temperature range of the melt, a high thermal conductivity coefficient and incongruent melts can be melted.
It is possible to cover the entire temperature range with this laser furnace, for which several furnaces with halogen and xenon lamps are usually required. 400 °C to 3000 °C can be achieved without the need for laser alignment or other optical system adjustments. The temperature of the melt zone can be directly monitored and recorded over the entire temperature range up to 3000 °C with an integrated radiation thermometer. This enables high-precision single crystal growth. The use of the RIKEN optical system ensures radiation stability. The diode laser source (DL source) is divided into 5 laser beams. A stable optical system ensures that the 5 heating laser beams do not fluctuate. The power of each individual heating beam is the same for all 5 beams. The laser beam is a continuous oscillation laser. The irradiation intensity is very stable over time.
Laser beam profile optimization -patented technology
A more gradual irradiation intensity distribution is adopted in the direction of crystal growth to help minimize thermal stresses within the material.
This optimization of the laser beam profile reduces thermal stresses on crystals as compared against a conventional laser FZ furnace consisting of a traditional top-hat laser power profile.
The irradiation intensity distribution of 5 laser head is circumferentially uniform.
A circumferential homogeneity of over 95% of irradiation intensity on the outer surface of the raw material is achieved (excellent circumferential uniformity as compared to a lamp-FZ platform).
Temperature can be precisely monitored and controlled in real time:
Temperature of molten zone can be directly monitored and recorded throughout the crystal growth process is possible with temperature range from 800 up to 3000 ? via a customized radiation thermometer.
Temperature monitoring spatial resolution of better than ?1.5mm.
The temperature of the melting zone can be controlled to the target temperature on the phase diagram with minimal temperature overshooting over a narrow 1? temperature window, ensuring growth of the desired compound.
Ideal for crystal production by the TSFZ method requiring long-term, unattended temperature control over a narrow 1? temperature window.
Reproducibility of measured temperature is within +/-1? .
Ideal for materials with high volatility
Compared to a traditional Halogen or Xenon lamp, the laser generates a much more concentrated energy profile at the FZ region. Less of the feed material is exposed to the higher temperatures generated by the energy source, lessening the amount of evaporative material which can contaminate the quartz tube.
The focused laser power acts to ablate any evaporates that may contaminate the quartz tube, leaving the quartz tube relatively clean in the laser-beam pass region.
Optional thin-wall protective quartz sleeves are available to help further protect the inside diameter of the quartz tube from damage or contamination.
Wide temperature range from 400 °C to 3000 °C
Reduction of thermal stresses due to adapted laser profile
Real-time temperature monitoring
Suitable for degassing materials
High laser stability due to patented design
High vision full HDTV camera for growth monitoring
Ubiquitous control possible by PC/Smartphone for remote monitoring/control of the crystal growth process
5 laser beams/heads
Laser power: 2000 watts in FZ region (400 watts × 5 beams)
Temperature range: 400 °C ~ 3000 °C (material dependent)
Temperature monitoring: 800 °C ~ 3000 °C (radiation thermometer)
±1 °C temperature reproducible over entire temperature range