When germanium melts, it will mechanically bond to the inner walls of the crucible liner. Upon cooling or re-heating, the difference in thermal expansion/contraction of the germanium in contact with the liner can produce enough stress to break the liner. We also find that the melt level of a material in the crucible directly affects the success of the crucible liner. Overfilling the crucible will cause the material to spill over and create an electrical short between the liner and the hearth. The outcome is cracking in the crucible. This is the most common cause of crucible liner failure. Placing too little material in the crucible or evaporating too much material before refilling can be detrimental to the process as well. When the melt level is below 30%, the e-beam is likely to strike the bottom or walls of the crucible which immediately results in breakage. Our recommendation is maintain a melt level between 30-80% and slowly ramp power up and down to prevent these complications. However, even when following these guidelines, the liners will still need to be replaced frequently.
Category: Evaporation Sources
Sub-Category: Crucible Liners for E-Beam Sources