Optimization of a carbon evaporator cell for MBE growth

A new design of carbon source using a S-shaped glassy carbon filament for p-doping and carbon deposition is presented. Due to the higher resistivity of the glassy carbon, lower current is needed to produce the same flux as in a source based on pyrolytic graphite filament. The source design is very compact and the use of water cooling is not mandatory. The results and simulations of the new design show a higher flux than the previously reported glassy carbon based source while avoiding hot spots that can cause an early filament degradation. Hole mobility vs doping level relation data on p-doped GaAs layers grown by molecular beam epitaxy using this new carbon source are shown. With this new C source GaAs (001) surface morphology flatness is preserved after depositing C, showing a reduced substrate heating radiation essential for operate in III-V solid source molecular beam epitaxy (MBE) systems.