Dark rectangular area in SEM

From: Yung-Jen Lin (yjlin_at_ttu.edu.tw)
Date: 10/12/04 

Date: 12 Oct 2004 08:28:58 -0700

Hello, everyone,
when I wanted to take SEM pictures of a Au-coated ceramic surface, I
often encounter one problem. I used a higher magnification image to
get a better focus. When I turned down to the desired (lower)
magnification, I usually found a rectangular dark area, which was the
scanning area of higher magnification. People suggested me to take
pictures of the nearby area.
My question is: what causes such a darken area after scanning of
e-beam? Some said it was caused by the contamination of the sample
surface. Others said it was caused by the defects of ceramics due to
high energy electron bombardment. Which one is correct? Or, what is
the real reason for it?
Thanks in advance.

Quantcast