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Abstract

We report on the electrical and defect characterization of Au Schottky diodes formed on single-crystal ZnO, before and after irradiating with high-energy (1.8 MeV) protons. Prior to bombardment we observed that several electron traps (E1-E4), with energies between 0.10 and 0.57 eV below the conduction band, are present in the ZnO. High-energy proton bombardment introduces two electron traps (Ep1 and Ep2), with extremely low introduction rates (η) of 2.4 and 1.9 cm −1 , respectively. Schottky barrier properties such as the reverse leakage current deteriorated from 1 × 10 −9 A for an unirradiated diode to 1 × 10 −6 A after bombarding it with a dose of 4.2 × 10 14 cm −2 protons. Compared to GaN we found that ZnO is remarkably resistant to high-energy proton bombardment.

Electronic properties of defects in pulsed-laser deposition grown ZnO with levels at 300 and 370meV below the conduction band

“…Note that for all temperatures between 160 and 190 K, the DLTS peaks could clearly be separated, yielding accurate values for the activation energy and apparent cross-section, as tabulated in Table 1. The E3 (E 300 ) level measured here is the same as that of the E3 defect measured in bulk-grown ZnO [4] and [5]. The E3′ (E 370 ) defect has not been reported for any bulk-grown ZnO and has only been seen in PLD-grown ZnO.…”

“…In the case of bulk-grown ZnO, only one of these defects, the E3 defect with an energy level at E C =300 meV is present [4] and [5]. We show that electron capture onto the E3′ defect in PLD-grown ZnO, with an energy level at E C =370 meV, increases strongly with increasing temperature.…”

“…Here, the E 300 defect is the same as the previously reported E3 defect for bulk-grown ZnO [4] and [5]. respectively, under conditions specified in the experimental procedure.…”

“…As in all semiconductors, defects play an important role in optimizing the characteristics of devices. Although the defects in bulk-grown ZnO have been studied in some detail by deep level transient spectroscopy (DLTS) [4] and [5], much less is known about the defects present in ZnO grown by pulsed-laser deposition (PLD).…”

Electrical characterization of 1.8 MeV proton-bombarded ZnO

“…DLTS in the temperature range 20-330 K revealed the presence of at least three levels in the as-grown ͑unirradi-ated͒ ZnO ͓curve ͑a͒ in Fig. 2͔, of which the properties and possible origin have been reported 10 and are also summarized in Table I. The most prominent of these defects, E1, is located at E T ϭE C Ϫ0.12 eV, while the second prominent defect has an energy level at E T ϭE C Ϫ0.27 eV.…”