MBE-like PLD systems
To obtain layer-by-layer growth of thin films, very stringent requirements are put on the deposition conditions, and thus on the deposition system. Especially for a technique like Pulsed Laser Deposition, the restrictions can be difficult to meet. Accurate control of substrate temperature, deposition pressure, energy of the incoming laser beam, and in-situ RHEED are necessary to obtain a MBE-like growth system. Twente Solid State Technology has developed such a system, which has all the features required to make layer-by-layer growth possible. The standard system will be built according to the user requirements.
The PLD-system consists of a PLD-chamber with a heater stage, a target stage, a high-pressure RHEED facility (including RHEED-gun and image acquisition system), and a loadlock. The heater temperature, the position of the heater, the pressure in the system and target selection are all computer controlled.
The PLD system for Layer-by-Layer (MBE-like) growth is a very sophisticated PLD-system. Special features are the very accurate temperature and pressure control during deposition, the in-situ RHEED facility, a loadlocking system for both the heaters and the target carousel. The system is fully automated, except for the loadlocking.
The temperature of the heaters is controlled by an external temperature controller and a separate current source. The temperature is measured by a thermocouple situated inside the heater body. Details about the heater can be found in the Heater product description.
The gas pressure and composition inside the system is controlled by Mass Flow Sensors for gas inlet and a stepper-motor controlled gate-valve to regulate the pressure. The control is carried out by an external pressure controller, and the pressure is measured by a baratron pressure sensor.
A in-situ RHEED is available with a high-pressure extension. The RHEED includes a RHEED-gun and control electronics, as well as a data acquisition system. More information about the high-pressure RHEED is available in the PLD-RHEED product description.
The target carousel can be introduced into and taken out of the chamber via the same loadlocking principle as the heater. The target carousel can contain up to 5 targets of maximum 25 mm (1") diameter. More information about the target stage is available in the Target product description.
A computer program sets the controls for gas inlet, pressure control and heater temperature. Furthermore, target selection and motion, heater positioning and shutter opening and closing are controlled by the computer.
Additional Options
The system can be extended with the following options:
- An extension of the computer program to include the control of the laser (if the laser being used can be programmed).
- An ion milling facility to clean the substrates prior to deposition.
Technical Specifications
- Minimum pressure of the system: <10-8 mbar (<7.5x10-9 Torr)
- Target to substrate distance: varying from 30 to 80 mm (from 1.2 to 3.2")
- Maximum pressure for in-situ RHEED: 50 Pa (0.4 Torr)
- Heater temperatures: up to 900 C
- Targets: up to 5 different targets at the same time, maximum 25 mm or 1" diameter.