Optical evidence for donor behavior of Sb in ZnO nanowires

Abstract

High-resolution photoluminescence (PL) experiments show that Sb doped ZnO nanowires exhibit shallow donor bound exciton (D0X) transitions at 3364.3 meV, which is shallower than the well-known In, Ga, Al, and H D0X transitions. The relative intensity of the Sb D0X transition scales with dopant concentration. Temperature dependent PL measurements show that the Sb D0X behaves like other D0X transitions with a thermal activation energy close to the spectroscopic binding energy. No evidence of an ionized donor bound exciton (D+X) is observed, consistent with the expectation from Haynes' rule that such a state would have a higher energy than the free exciton.