Observation of Ni3+ acceptor in P-type Ni(P):SnO2

Abstract Ni dopants typically exist as Ni 2+ oxidation state in metal oxides. We report that as Ni is co-doped with P in Ni(P):SnO 2 , P promotes Ni 2+ into Ni 3+ , which acts as acceptor and coverts n-type SnO 2 to p-type conduction. Significant hole concentration (4.5 × 10 18  cm −3 ) of p-type Ni(P):SnO 2 can be obtained. The chemical state of Ni 3+ in Ni(P):SnO 2 is verified by ultra-violet and x-ray photoelectron spectroscopy. With the developed p-Ni(P):SnO 2 , transparent p-Ni(P):SnO 2 /i-SnO 2 /n-ITO p-i-n structure was fabricated and characterized: low leakage-current (8.41 × 10 −5  A at −5 V), turn-on voltage (4.68 eV), good transmittance (85%), and small ideality-factor (1.73).