Liquid Alloy Source for Dopants
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
In silicon molecular beam epitaxy (Si MBE), a dopant beam is used in neutral or ionized form to simultaneously dope Si films during epitaxial growth. Thermally-generated neutral beams are preferred for this purpose because the system is simple to implement and the growth is better understood and easy to accomplish. Unfortunately, the choice of N type dopants is severely restricted due to practical limitations. All the N type dopants have extremely high vapor pressures. This has several drawbacks. First, there is appreciable flux at temperatures as low as 250oC, typically used during bake-out and these species deposited on vacuum parts will re-evaporate when these parts warm up during growth.