Design considerations for exponentially retrograded silicon hyperabrupt varactors

Avalanche breakdown voltage V
B
, space-charge width at breakdown W
B
, and
C-V
index
n
of exponentially retrograded silicon hyperabrupt p
⁺
-n junctions have been calculated for various impurity distributions. Empirical relations are obtained expressing W
B
, V
B
, and the maximum value of
n
in terms of impurity profile parameters of the retrograded region. Applications of these relations in the design of hyperabrupt varactors is indicated.