High Pressure Czochralski Process Furnace HCO*
The compact tabletop Czochralski Process Furnace HCO is capable to pull single crystals out of a melt-filled crucible under ambient gas pressure of up to 150 bar. The gas management system enables adjustable pressures, flow rates and process atmospheres as well as the evacuation of the process chamber. Typically used gases are pure oxygen, argon or variable mixtures of both, but almost any other gas, also reactive gases which interfere with the melt during the growth process, can be introduced.
High pressure atmospheres have two effects on crystal growth out of melts. On the one hand, high pressures prohibit the separation of the volatile component from the melt and prevent stoichiometry changes. On the other hand, high-pressure atmospheres of defined pure and mixed gases can support the formation or prevent the decomposition of certain desired phases and suppress the formation of impurity phases. As the HCO system contains independent mass flow control for each gas, individual partial pressures and flow rates can be freely adjusted. This worldwide unique setup allows the user to rule the growth of materials, which are difficult or impossible to create at low pressures due to the higher volatility of their elements or to a metastable nature of the certain phase.
The crucible can have up to 70 mm inner diameter and enables the growth of crystals with a diameter of up to 2.5”. The crucible material which suits best in terms of the crucible-melt interdependence can be selected out of a wide range of possible substances in order to minimize the crucible impact on the melt composition. Depending on the intended process and the crucible material, temperatures of up to 1700 °C can be achieved with a resistance heating setup.
In order to pull the crystal rod, we use a magnetically coupled feed through system. This allows highly precise, homogeneous pulling rates and rotations. A fast gear is implemented for comfortable set-up procedure. The whole movement system is completely capsuled without pressurized bearings and is employable at all possible pressure regimes.
A lot of processes require an inert atmosphere with partial pressure of oxygen which is as low as possible. The optional active argon gas purification system GRS removes reliably oxygen particles from flowing argon and achieves O2 concentrations down to 10-12 ppm under high pressure conditions.
The entire set of experimental parameters such as linear and rotational movements of the pulling drive, gas mixture, gas flow, gas pressure and the heating power are controlled by a build-in computer. A comfortable software application combines all relevant system information and process adjustments in one user interface unit. A very important characteristic is the highly developable and easily expandable design of the HCO system, which allows custom-tailored constructions and specifications according to individual needs as well as the installation of add-ons in an easy and cost-efficient way.
Technical details:
- Gas pressure: up to 150 bar in the process chamber
- Freely and independently adjustable partial pressures and flow rates of different gases (typical: Ar and O2)
- Vacuum: down to 10-5 mbar, wide diameter turbo-pump connections
- Crucible inner diameter: up to 70 mm
- Crucible volume: 300 ml (in the standard configration)
- Temperature: up to 1700 °C
- Pulling system: precise magnetically coupled pulling and rotation feed through system without pressurized bearings
- All system parameters are comfortably controllable and adjustable via a build-in computer and a software application
- Power ramp and traveling ramp functions
Required laboratory connections:
- Gas supply with the intended pressure
- Exhaust air system
- Energy supply: 3-phase AC, 50 Hz, 400 V
- Cooling water