Two‐stage arsenic cracking source with integral getter pump for MBE growth

The design is described for a two‐stage arsenic evaporation and cracking source that incorporates an integral getter pump which effectively converts As4 to As2 as well as reduces arsenic oxides. The results show that the conversion efficiency from As4 to As2 is approximately 85% at 700 °C and the in beam background As–O is reduced during growth by a factor of 6 for our system to approximately 1×10−10 Torr. We have measured the room temperature As2 sticking coefficient on GaAs and find that it increases from near zero for As4 to 0.5 for As2. The effect of the cracking has been evaluated by measurements on layers and devices grown with this arsenic source.