Temperature dependence of Cu ₂ O orientations in the oxidation of Cu (111)/ZnO (0001) by oxygen plasma

Abstract

The role of temperature on the oxidation dynamics of Cu 2 O on ZnO (0001) was investigated during the oxidation of Cu (111)/ZnO (0001) by using the oxygen plasma as oxidant. A transition from single crystalline Cu 2 O (111) orientation to micro-zone phase separation with multiple orientations was revealed when the oxidation temperature increased from 300 • C to higher. The experimental results clearly showed the effect of oxidation temperature with the assistance of oxygen plasma on changing the morphology of Cu (111) film and enhancing the lateral nucleation and migration abilities of cuprous oxides. A vertical top-down oxidation mode and a lateral migration model were proposed to explain the different nucleation and growth dynamics of the temperature-dependent oxidation process in the oxidation of Cu (111)/ZnO (0001).

Epitaxial Strain-Induced Growth of CuO at Cu2O/ZnO Interfaces

“…However, the complex pattern seen in Figure f can be described as two single-crystal zone patterns ([1̅ 10] and [11̅0]) twin related with a 180° rotation around the common [111] axis. Such a twin relation has previously been reported for Cu 2 O nanoparticles and in Cu 2 O film upon oxidation of a single-crystal Cu. − The additional reflexions located 1/3 and 2/3 between {111} rows are due to multiple scattering, i.e., the two twin regions are partly overlapping and the electrons will, due to their short scattering mean free path, scatter from both twin orientations resulting in additional reflexions. From the indexed patterns in Figure , it can be concluded that the substrate and the Cu 2 O films has the two orientation variants: (111)[11̅0] Cu2O ∥(0001)­[112̅0] ZnO and (111)[1̅10] Cu2O ∥(0001)­[112̅0] ZnO .…”

Probing Defects in Nitrogen-Doped Cu2O

“…Cu 2 O and Cu 2 O:N films were obtained via the post-oxidation of Cu (111) films that were initially deposited on c-plane Al 2 O 3 buffered with a 400 nm thick, semi-insulating ZnO film20. Nitrogen doping was achieved by introducing a nitrogen plasma through a radio-frequency (RF) plasma gun during the oxidation process.…”

“…Shorter or longer treatment times would result in undesired phases of Cu and CuO, respectively. More details can be found in our previous report20.…”

Engineering of optically defect free Cu_2O enabling exciton luminescence at room temperature

“…For example, the high-temperature oxidized films on ZnO show an extra Cu 2 O (200) peak at 42.3°, which is not seen in the epi samples and lowtemperature oxidized sample. Overall, the phase homogeneity issues are critical but have been addressed/mastered earlier [18,19], providing the grounds to focus on the evolution of the PL signatures as a function of oxidizing temperature. [10][11][12][13].…”