Composition Dependence of Optical Properties and Band Structures in p-Type Ni-Doped CuO Films: Spectroscopic Experiment and First-Principles Calculation

Abstract

Despite much attention on the photoelectronic device applications of CuO-based materials, a thorough analysis of optical properties and electronic band structure of Ni-doped CuO films is still necessary. Here, the calculation based on the density functional theory revealed a strong hybridization of O 2p and Cu 3d orbits near the conduction band minimum (CBM) and valence band maximum (VBM) of CuO films. The Ni addition is found to enhance the carrier mobility, because the weaker localization of O 2p states at the VBM is observed in 50 atom % doped CuO. To confirm the theoretical results, the ellipsometric spectra of solution-processed CuO films doped by Ni ions (from 0 to 50 atom %) were fitted, and the optical constants were uniquely extracted. The optical conductivity has a linear increase with the Ni doping concentration, which results from the decreased electron traps. Besides, the band gap was found to be modulated in a range of 2.22–2.37 eV owing to the quantum confinement effects. The variation trend is confirmed by the first-principles calculation, where the computational indirect band gap is 1.27 and 1.79 eV for pure CuO and 50 atom % Ni-doped CuO. Four electronic transitions are observed at ∼2.75, 3.27, 4.01, and 4.90 eV, and the physical origins have been discussed.

Fabrication of clay soil/CuFe2O4 nanocomposite toward improving energy and shielding efficiency of buildings

“…The energy band gaps of prepared structures were examined by Kubelka–Munk theory 21 , 25 , 29 . Obviously, CuFe 2 O 4 curve illustrated two energy band gaps (2.31 eV and 1.43 eV), corresponding to the energy gap related to CuFe 2 O 4 and formed CuO, as confirmed by XRD pattern 30 – 33 . The wide light absorption around near IR can be associated with the local surface plasmon resonance and light scattering.…”

Prospect of making XPS a high-throughput analytical method illustrated for a CuxNi1−xOy combinatorial material library

“…6 Cu 2 O has a smaller bandgap (2.1-2.3 eV) with also weak visible light absorption, but with higher hole mobility, >100 cm 2 V s À1 . 7,8 Combining both binary oxides promises to open a route to tune optoelectronic and structural properties to arrive at a new material, optimized for hole-conduction, electron-blocking 9,10 with ideal interface energetics 11 as HTL in HaP-based optoelectronic devices.…”

High Responsivity and External Quantum Efficiency Photodetectors Based on Solution-Processed Ni-Doped CuO Films

“…Among the various transition metal dopants, Ni ions have a similar ionic radius to Cu ions. Besides, the large band gap of NiO can widen the energy band of the CuO film . Therefore, it is important to investigate the effects of Ni doping on the photocurrent, responsivity, and detection range of Cu 1– x Ni x O film photodetectors.…”