Direct Observation of the Valence Band Edge by in Situ ECSTM-ECTS in p-Type Cu₂O Layers Prepared by Copper Anodization

Abstract

Polycrystalline Cu 2 O layers have been selectively grown by electrochemical anodization of polycrystalline Cu electrodes in an alkaline medium (pH 12.85). Uniform layers with thicknesses around 100 nm have been obtained. Using electrochemical impedance spectroscopy, it was concluded that the Cu 2 O films behave as a p-type semiconductor. The Mott-Schottky plot gives a value for the flat band potential of U FB ) -255 mV vs silver/silver chloride electrode (SSC), an estimated carrier density N A ) 6.1 × 10 17 cm -3 , and the space charge layer width was calculated to be W SCL ) 9 nm at a band bending of 120 mV. The electronic structure of the Cu|Cu 2 O|electrolyte interface was for the first time probed by in situ electrochemical tunneling spectroscopy. The use of in situ electrochemical scanning tunneling microscopy allows us to directly observed the valence band edge and determine its position against the absolute energy scale to be E VB ) -4.9 eV. Finally, we constructed a quantitative electronic diagram of the Cu|Cu 2 O|electrolyte interface, where the positions of the valence and conduction band edges are depicted, as well as the edge of the previously reported electronic subband.

DFT Study of Azole Corrosion Inhibitors on Cu2O Model of Oxidized Copper Surfaces: I. Molecule–Surface and Cl–Surface Bonding

“…The same is true on Cu 2 O surfaces, namely, the E • EA − Φ contribution of Equation (A1) is negative for all the three molecules. In particular, the experimental work-function of Cu 2 O is about 5 eV [63], whereas the calculated electron affinities of Mol…”

Electrical Resistance Evolution of Cu Redistribution Layer Electroplated on a Si Interposer

“…From the results that chlorine is accumulated at the RDL Cu/oxide interface at stage II, and that the recrystallization of the RDL Cu layer leaves further piling of impurity chlorine at the RDL Cu/oxide interface at stage III, it is logically thought that the chlorine diffuses into Cu 2 O layer due to concentration gradient of the impurity chlorine and becomes an acceptor impurity in the Cu 2 O layer. The Cu 2 O layer is known as a p-type semiconductor [27,28] and can have the solubility of a solute, the impurity chlorine. Following Reiss [29], we may write the reaction…”

Microstructures and Photovoltaic Properties of Zn(Al)O/Cu2O-Based Solar Cells Prepared by Spin-Coating and Electrodeposition

“…Copper oxides (Cu 2 O) are known to be p-type semiconductor oxides, and the crystal structure of Cu 2 O is cubic system with a space group of Pn3m [1], as shown in Figure 1a A maximum efficiency of 5.38% has been obtained for Cu 2 O solar cells fabricated by high-temperature annealing and pulsed laser deposition [2]. Cu 2 O-based solar cells fabricated by electrodeposition and photochemical deposition have been reported [3][4][5][6][7][8][9][10][11][12], and zinc oxide (ZnO)/Cu 2 O thin film solar cells prepared by electrodeposition have also been reported [13][14][15][16][17][18][19][20][21][22]. Electrodeposition is a low-temperature method for solar cell fabrication with a low process cost.…”