Effect of electrical field on annealing of thin film bismuth

[christopher.s]

I have been reading recently on the properties of evaporated thin film bismuth, particularly grain size and resistivity. Usually evaporated bismuth is amorphous and semimetallic, with very small grain size. Grain size can be increased and resistance lowered by annealing the film. It has been shown that the temperature of annealing as well as the cooling rate can have a dramatic effect on the resistance of bismuth. I was curious as to what would happen if the bismuth were under the influence of an electric field, by say passing a small current through the film as it were annealed. I'm not sure if it would have any effect at all on grain size or resistance, and to be honest I have basically no understanding of the physical mechanisms of annealing or what is happening on an atomic level. If anybody has some insight, or can offer explanations on what determines how the bismuth anneals atomically, I would appreciate it. Thanks!

 

[christopher.s]

I guess I could have done a little more research before posting the question, but I have a little more information to go on now. There is not a lot of literature of the effect on electric or magnetic fields of thin films during annealing, but there is a lot of information on annealing cold rolled steels or aluminum with and without applied electric fields. As this paper¹ shows, an electric field applied to cold rolled aluminum does not change mechanism of recrystallization but it does enhance cube texture. I also read some papers on the effect of electric field applied during evaporation of Ti thin films. Fascinating stuff! I am not sure how much the grain structure of bismuth will be effected though, from what I have read during annealing it tends to "ball up" due to surface tension.

The reason I ask about the annealing is that I wish to improve the electrical and optical qualities of thin film bismuth, particularly by lowering resistance compared to evaporated films for a given film thickness (and lowering the specific heat of the film), and to decrease transmission and reflection of infrared.

1 - http://www.ysxbcn.com/upfile/soft/2008425/2008425103827363.pdf