Sample 6 & 5

 16
 14
 12
 10
 E8 -- Sample 6
 S6 Sample 5
 4
 2
 4-- -------------------


 -2 33 4.
 microns

Figure 61. This is a plot of the etched sample 5 line scan superimposed over the unetched
sample 6 line scan. There is a negative area where material has been removed close to
the base of the gold star.


Figure 61 shows a plot of the etched Sample 5 line scan superimposed over the unetched

Sample 6 line scan. There is no sign of build up or deposition as was observed in Figure

60. Also in Figure 61, there is a negative area where material has been removed close to

the base of the gold star. This is an indication that the gallium arsenide is being etched.

Tilting the samples during AFM analysis allowed further investigation of the edge

profile, specifically for possible undercutting of the gold. There appears to be no

undercutting observed in the results as would be expected from a purely chemical etch

mechanism. Thus, the AFM results show that the presence of gold during the etching of

gallium arsenide has no visible influence using these methods.

4.2 Field Emission Scanning Electron Microscopy and Energy Dispersive
 Spectroscopy

 Sample 1 is unetched gallium arsenide with gold stars and is used as a guideline

to determine if the etched samples, samples 2 and 3, exhibited any change in surface

characteristics after being etched. A gold star on unetched sample 1 is clearly visible in