Hi Trung; You might try looking up the alloy phase diagrams of the material you want to bond to . For silicon, various silicon and germanium alloys exhibit melting temperatures below 350 C. Also , Tom Eagar of MIT wrote some articles a few years ago on low temperature eutectic alloys. The eutectics will melt at much lower temperatures than either material alone. I found some in a project on low temperature fusion bonding I did about 5 years ago , but I forget exactly which alloys I used , and I found them much as I described above. regards Jdubow