The Early Stages of Etching

In order to develop an understanding of the initial formation of holes, high magnifications were used to study how etching occurs in the first hour.

Note: This particular batch was etched in 70 degree 6M NaOH. This would yield smaller diameter pits than the standard 80 degree etch.

20 minutes ( --- = 1.63 um) 25 minutes( --- = 1.81 um) 30 minutes( --- = 1.81 um)
Photo of etchin after 20 minutes
       
35 minutes( --- = 2.65 um) 40 minutes( --- = 1.95 um) 45 minutes( --- = 1.93 um)
photo of etching after 35 minutes
     
50 minutes( --- = 2.55 um) 55 minutes( --- = 2.78 um) 60 minutes( --- = 2.55 um)
photo of etching after 50 minutes