Exploring the formation of intrinsic p -type and n -type defects in CuO

Abstract

CuO (cupric oxide) is a well-known p-type semiconductor, suitable for solar cell photovoltaic applications. However, due to the easy formation of defects and Cu-rich layers at the copper(II) oxide heterointerface, commercial application is yet to be successfully implemented. Density functional theory calculations have been employed to study the formation of intrinsic defects and their effect on the electronic properties of CuO. Native impurities were observed, depending on the synthesis conditions, to render the conductivity to p-type or n-type at a low energetic cost, yet with states embedded deep in the electronic band gap. Respective defect pairs, effectively determining the majority charge carriers, were observed to cluster in near proximity of each other, lowering the formation energy substantially. Hydrogen passivation was illustrated to have a positive effect on deep defect states in p-type CuO, without affecting the n-type counterpart. Outlined results were found to support the experimentally observed low photoresponse of CuO and further illustrate some of the difficulties related with achieving high-performance samples.

Influence of the Defect Stability on n-Type Conductivity in Electron-Doped α- and β-Co(OH)2 Nanosheets

“…This limitation arises, in part, because electronic doping of TMOs typically occurs via intrinsic lattice defects and compositional nonstoichiometry. − Depending on the formation energies of the various structural defects within the crystal lattice (i.e., vacancies and interstitials of either the metal cation or oxygen), any given oxide composition will show a marked preference for either n- or p-type doping. Late-first-row TMOs such as cobalt, nickel, and copper oxide exhibit low formation energies and good stabilities for metal cation vacancies (V M ), and the substoichiometric forms of these oxides, M 1– x O, are p-type semiconductors (Scheme a). − In contrast, oxides such as TiO 2 and ZnO readily form oxygen vacancies (V O ) and show n-type conductivity when substoichiometric in oxygen (Scheme b). − In both cases, it is difficult to form mobile carriers of opposite polarity because the relevant structural defect is either energetically inaccessible or highly unstable. − It is critical, therefore, to understand the structural factors that dictate the defect formation energy and stability in TMOs in order to achieve ambipolar doping.…”

A core‐shell structured diffusion‐bubbling membrane for efficient oxygen separation: Formation and transport properties

“…A chain breakage leads to two new chains formation and an oxygen pseudovacancy at the end of one of them, which captures free oxygen ion; the connection of any two chains is followed by the release of a terminal oxygen ion that is captured by the nearest pseudovacancy, etc. Copper oxide electronic conduction mechanisms are comprehensively described in the literature 31–33 …”

“…Copper oxide electronic conduction mechanisms are comprehensively described in the literature. [31][32][33]…”

Oxygen separation diffusion-bubbling membranes

“…Its electronic and structural properties have been studied intensively because of the high-temperature superconductivity discovery described comprehensively in the literature. [52][53][54][55][56][57] Oxygen permeation flux j 0 O 2 through the membrane shell can be limited by both chemical diffusion and surface exchange. When the thickness (L s ) of the membrane shell L s 4 L ch (L ch is the characteristic thickness defining the shell thickness that corresponds to the transition from chemical diffusion limitation to the state when the rate of oxygen permeation through the shell is controlled by the surface exchange 58 ), the oxygen flux is limited by chemical diffusion and given by the following equation: 31…”

“…Its electronic and structural properties have been studied intensively because of the high-temperature superconductivity discovery described comprehensively in the literature. 52–57…”