Epitaxial growth of Cu2O and ZnO/Cu2O thin films on MgO by plasma-assisted molecular beam epitaxy

Heteroepitaxial Cu2O thin film solar cell on metallic substrates

“…Although some previous efforts have demonstrated Cu 2 O films with either high carrier mobility (over 50 cm 2  V −1  s −1 ) or high carrier concentration (over 10 16  cm −3 ), deposition of Cu 2 O films having both high carrier mobility and concentration without using single crystalline substrates has been considered very challenging in the field. To our best knowledge, a recent work only reported high carrier mobility of 50–70 cm 2  V −1  s −1 as well as high concentration of ~1 × 10 16  cm −3 from very thin (70 nm thick) epitaxial Cu 2 O films on (100) MgO single crystal substrates23, similar to the values reported in this study on technical substrates that can be scaled to very large-areas at low-cost.…”

“…Unlike defective polycrystalline films, single-crystal-like, epitaxial Cu 2 O films are expected to greatly reduce the defects by eliminating high angle grain boundaries which are major sources for defects generation and as a result, to have much better electronic and optical properties of the films. Several groups have reported epitaxial growth of Cu 2 O films with improved electronic properties via several deposition methods such as pulsed laser deposition (PLD), molecular beam epitaxy, and sputtering2122232425. Matsuzaki et al 22 reported the improved majority carrier (hole) mobility from epitaxial Cu 2 O films grown via PLD.…”

Influence of target power on properties of CuxO thin films prepared by reactive radio frequency magnetron sputtering

“…For further understanding and improvement, both the thin film properties (transport, optical, structural) and interface defects should be investigated. Cu 2 O (cuprous oxide) can be fabricated by several different techniques such as thermal oxidation [5], direct current (dc) [6,7] or radio frequency (rf) [8] reactive sputtering, molecular beam epitaxy [9] and electrodeposition [10]. Among these different techniques, reactive rf magnetron sputtering has a good stoichiometry control of Cu 2 O because there are several different growth parameters that can be varied in order to form either Cu-rich or O-rich phases.…”

Single phase, single orientation Cu2O (1 0 0) and (1 1 0) thin films grown by plasma-assisted molecular beam epitaxy

“…Although reasons for this are still debated and different epitaxial relationships have been reported [7,8,13,14], density functional theory calculations show that the Cu 2 O (1 1 0):CuO surface has the lowest energy, and generally the nonpolar Cu 2 O (1 1 0) surfaces have lower energies than the polar Cu 2 O (1 0 0) surfaces [12]. Lattice mismatch seems to be less important than surface energy in determining the preferential growth direction [7].…”

“…The development of such a structure would require synthesis by thin film methods, and molecular beam epitaxy (MBE) provides precise control over many deposition parameters and generally yields high quality material. MBE synthesis of Cu 2 O on MgO substrates has been demonstrated using pure atomic oxygen [7,8,9], however no reports of a diluted oxygen plasma have been made to date. Also, growth on MgO (1 1 0) surface has been reported by sputtering [10] and pulsed laser deposition [11], but not by MBE.…”