1236 npMgF2 Temp Series structural comparisons to 1085 npMgF2

ByGreg Madejski

As we run our CCD (Central Composite Design for Optimizing SERS Substrates, SERS Measurements on 150C, 250C, 350C 1236 npMgF2), we have also been gathering TEM/SEM structural information about pore distributions and MgF2 grain structure. This post contains images about materials and compares them to information we know about wafer 1085, one of our original MgF2 materials.

Pore Histograms

1085 based Materials

1085 NPN Center Montage, from SiMPore
1085 NPN Edge Montage, from SiMPore

 

1085 npMgF2, 17500x. Pores are scummed over, but probably were not when made.
1085 npMgF2, 13500x. Pores are scummed over, but probably were not when made. Same trend holds over the smaller magnification.

 

1236 based Materials

1236 NPN Center Montage

 

Temp Series

1236 npMgF2 150C 50nm
1236 npMgF2 250C 50nm
1236 npMgF2 350C 50nm

There seems to be a small increase in pore diameter as the MgF2 temperature increases; some of the volcano might be resorbing into the thicker film.

Structural Information

1085 npMgF2

TEM tilted images +/- 14 deg, 2 deg increment. The TEM confirms that the pores are closed (maybe a different material than MgF2; the crystals don’t look the same), and the lack of projection shows the volcanoes are shallow.

 

1236 npMgF2

1236 npMgF2 150C +6to+20deg. 50nm MgF2.

 

1236 npMgF2 250C -14to+14deg. 50 nm MgF2.

 

1236 npMgF2 350C -14to+12deg. 50nm MgF2

With this series, the npMgF2 structure does seem to change significantly (by eye) between 150C and 250C, and not so much by 350C.

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