Towards optical hyperdoping of binary oxide semiconductors

Abstract

Surface structuring with ultrashort laser pulses is of high interest as a scalable doping technique as well as for surface nanostructuring applications. By depositing a layer of antimony before the irradiation of ZnO, we were able to incorporate a large quantity of Sb atoms into the single crystalline region of the laser modified surface for potential p-type doping. We have studied the incorporation of antimony and the material properties of laser-induced periodic surface structures (LIPSS) on c-plane ZnO upon femtosecond laser processing at two different peak fluences. We observe high spatial frequency LIPSS with structure periods from 200–370 nm and low spatial frequency LIPSS with periods of 600–700 nm. At a fluence of 0.8 J/cm2, close the ablation threshold of ZnO, the LIPSS are single crystalline except for a few nanometers of amorphous material. At a peak laser fluence of 3.1 J/cm2, they consist of polycrystalline and single crystalline ZnO areas. However, the polycrystalline part dominates with a thickness of about 500 nm.