Avalanche region width in various structures of IMPATT diodes

The avalanche region of one-sided and two-sided abrupt junctions has been studied. These are the structures most commonly utilized for IMPATT diodes. Numerical results are presented which show that n⁺-p Si diodes have much narrower avalanche regions, due to the unequal ionization rates in Si, than the complementary p⁺-n type. The implications of these results with respect to IMPATT diode design are discussed.