RHEED is an in situ real time monitoring tool revealing material structure, growth rate, and layer-by-layer changes. Several techniques, such as laser deposition, CVD, MOMBE require higher pressure in the process chamber during growth. The working gases may be very reactive.
Even in such difficult conditions, STAIB RHEED Systems provide effective analysis of growth from the in situ RHEED observations. The patented TorrRHEEDTM overcomes the potential effects of high pressure environments with a design that ensures the best filament life and excellent RHEED patterns. Patented STAIB beam steering, electronic beam rocking, azimuth control, and multiple coil systems, provide the user with the capability to monitor a wide range of possible sample positions.
For pressures up to a few 10 mTorr: the integrated single differential pumping stage
For gas pressures inside the vacuum chamber up to a few 10 mTorr, a single differential pumping stage is sufficient to ensure long lifetime of the filament. The pumping is integrated into the gun, providing an efficiency (expressed as the ratio between the chamber and the gun pressure) up to a factor of 1000. This maintains the pressure inside the gun at a level for efficient operation of the gun and a long lifetime of the filament.
For pressures up to a few 100 mTorr: the double differential pumping configuration (TorrRHEEDTM )
Since scattering of electrons becomes stronger and the mean free path of electrons is reduced in this pressure range, the TorrRHEEDTM system is configured with shorter working distances on both the gun and screen sides of the sample plus a second differential pumping stage. Additionally, features from the single pumped system are incorporated to ensure long filament life. High beam voltage (30 to 50 kV) is recommended for improved operation at such higher pressures, to further reduce the scattering effects.