P-Type Characteristic of Nitrogen-Doped ZnO Films

Zinc oxide (ZnO) is a promising material for emerging electronic and photonic applications due to its wide direct band gap and large exciton binding energy. Despite on-going developments, the control of the conductivity type in ZnO films continues to be a challenge. Stable p-type ZnO is required in order to fabricate standalone ZnO-based devices. Nitrogen is considered as a promising candidate to produce a shallow acceptor level in ZnO, since it has similar radii and electrical structure to oxygen. In this experiment, we utilize the low cost sol–gel spin coating technique to fabricate nitrogen-doped ZnO (ZnO:N) films. All films show great optical transmittance above 80% in the visible region. ZnO:N film at 15 at.% doping concentration shows strong UV emission and exhibits low resistivity. A p–n homojunction device based on ZnO:N shows characteristic of a typical rectifying diode, with a turn-on voltage of approximately 1.2 V