 RHEED System |
The
RHEED gun
RHEED guns from S T A I B INSTRUMENTS provide
dedicated electron optics systems for diffraction studies, in the range of
10 to 60 keV. By combining electrostatic and magnetic elements, the gun
produces a high brightness, small size, and low divergence beam, with
extremely low outgassing. The gun mounts completely outside the chamber.
The optics are prealigned and need no time consuming adjustment. The
system can be serviced onsite and is bakeable. Operation at higher
pressure is possible and, if necessary, an efficient differential pumping
option is available.
The
power supply
The power supply, up to 60
keV, is compact and designed with state of the art electronic components.
Guns settings, such as energy, filament current, and beam intensity, are
displayed using digital readouts. The power supply is REMOTE CONTROLLED by
a compact control panel to adjust the beam intensity, focus, and position.
The system is equipped with a DIAGNOSTIC capability, which allows a quick
and complete test of the RHEED system.
Beam
blanking
The electron beam can be turned on and off
using this option, keeping the electron load on the sample very low.
The blanking signal can also be triggered synchronously with external
signals to improve the use of RHEED in the presence of stray magnetic
fields or to investigate rotating samples.
Beam
rocking
For RHEED analysis, the electron beam must
impinge onto the surface at grazing incidence. The unique feature, BEAM
ROCKING, allows the precise adjustment and variation of the incidence
angle using electronic controls, without moving the sample. This feature
is most useful for analyses performed at a fixed sample position.
Differential pumping
The standard electron gun is designed to
operate at higher pressure, in the 10-4
torr range, but the lifetime of the cathode may be reduced. The
differential pumping option (TorrRHEED) allows routine operation at higher
pressure and/or with reactive gases. Efficient pumping of the cathode
section offers unbeatable versatility.
Computer control
The RHEED system can be entirely
computer controlled. The RHEED
gun controller includes an Interface Module and a Software Package,
and makes use of the RHEED very precise and repeatable. Userīs parameters
can be saved and retrieved, the beam can be turned on and off using the
BEAM BLANKING option, and the incidence angle can be adjusted using the
BEAM ROCKING feature.
Fluorescent
screens
Available in different sizes, the
screens are designed to reach high spatial resolution and best contrast. A
protective aluminium coating ensures good electric contact, blocks stray
light from inside the vacuum chamber, and improves the contrast of RHEED
diagrams.
RHEED
data acquisition and analysis
RHEED Vision
is a powerful data acquisition tool adaptable to every existing RHEED
system. Both image processing and real time analysis can be performed. All
routines are simply selected through pull-down menus. A large number of
data reduction routines are selectable. Additional hardware control
modules are available, as for phase locked epitaxy, shutter controls,
laser pulse triggering, etc...
Applications
S T A I B INSTRUMENTS RHEED
systems allow insitu monitoring of the surface structure and are widely
used in the following applications:
- Crystallography
- Superconductors
- Molecular beam epitaxy (MBE)
- Chemical vapor deposition
- PLD, CVD, MoCVD
- Metallurgy
- Thin film deposition
- Coatings
