Means and method for a liquid metal evaporation source with integral level sensor and external reservoir

A liquid metal evaporation source for use in Molecular Beam Epitaxy (MBE) or vacuum deposition processes, said source comprising:

• a high temperature evaporator;
• an intermediate temperature hollow transport tube;
• and
• a low temperature hollow reservoir cylinder with close-mating cylindrical piston;
• wherein each of said evaporator, said transport tube and said reservoir cylinder include a radiant resistive heater element with a thermocouple to sense and regulate the heater power, and
• wherein at least one conducting probe is used to sense contact with liquid metal in said evaporator by making a low resistance electrical contact in which the level of said conducting probe can be used to control a position of said piston in said reservoir cylinder via an automatic feedback control circuit which drives a motor attached to a linear motion vacuum feedthrough which in turn is attached to said piston and is used to regulate a constant height of said liquid metal in said evaporator to maintain a constant evaporation rate of said liquid metal from said evaporator at a fixed evaporator temperature.