Fig. 5.14 and Fig. 5.15 show the effects of varying
the width of the mask for the vertical n-doped area on the on-resistance and the
maximum electric field, respectively. Reducing the mask width by
increases the on-resistance to values which are similar to those of the
standard device. An increase of the mask width by
0.5 
m results in
an approximately 4% lower on-resistance than in the optimized device.
Reducing the width of the n-doped area decreases the maximum of the electric field by approximately 12% compared to the optimized device. In the device with increased width of the n-doped area the maximum of the electric field is approximately 16% higher than for the optimized device. The critical field of 300 kV cm- 1 is reached for a gate voltage of approximately 110 V.
To achieve an improved on-resistance and reliable device performance the variation of the width of the vertical n-doped area has to be monitored.
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