Stark Effect on Impurity Levels in Diamond

In this article we present our experimental results on the Stark effect of the shallow impurity levels of $p$-type semiconducting diamond (IIb). The shift of the levels is found to be quadratic in the applied electric field, and to tend towards the ground state. No splitting of the fourfold degenerate levels was observed; instead, a broadening of the levels, quadratic in the field, is attributed to an unresolved splitting. The over-all behavior of the spectrum agrees with the group-theoretical predictions, and the estimated Stark coefficients are in reasonable relation with those of silicon and germanium.