Electrical characterization of He+ irradiated n-ZnO

ZnO Schottky barrier diodes (SBD's) were fabricated with 20/80/40/80 nm Ti/Al/Pt/Au ohmic contacts on the O face and circular 0.5 mm in diameter 50 nm thick Ru Schottky contacts in the Zn face. The carrier concentration of the ZnO prior to irradiation was approximately 5 × 1016 cm−3. These diodes were irradiated with 1.8 MeV He+ with fluences ranging from 1 × 1012 cm−2 to 2 × 1013 cm−2. Deep level transient spectroscopy (DLTS) was used to study the defects introduced. These measurements revealed that this irradiation introduced a defect with an energy level at 0.55 eV below the conduction band. The introduction rate of this defect for 1.8 MeV He+ ions was calculated to be 220 ± 20 cm−1. This appears to be the same defect that is introduced during proton irradiation of ZnO. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)