Structural, optical and electrical properties of delafossite CuGaO₂films grown by sol-gel method

Abstract

Transparent p-type conductive CuGaO 2 films have been fabricated on sapphire substrates by sol-gel method. The stable sol solution for CuGaO 2 were formed by copper(II) acetate monohydrate and gallium(III) nitrate hydrate, and the c-axis orientation of CuGaO 2 films were strengthened with increasing annealing temperature. The pure phase CuGaO 2 film was obtained at 900 o C for 30 min in N 2 atmosphere, and its microstructure, compositions, optical and electrical properties were analyzed. It was found that the sol-gel derived CuGaO 2 films show a high optical transparency (60-80%) in the visible region, the direct and indirect band gaps were approximately 3.56 and 3.24 eV, respectively. It shows a crossover from the thermal activation behavior to that of three-dimensional variable range hopping from the temperature-dependent electrical conductivity at about 160 K.

Preparation and Characterization of Radio Frequency Sputtered Delafossite p-type Copper Gallium Oxide (p-CuGaO2) Thin Films

“…2 A similar appearance of single-phase CuGaO 2 at annealing temperatures of 900 °C has been reported in an earlier study. 10 The diffraction peaks determined in films annealed at 900 °C and above indexed well to delafossite CuGaO 2 (JCPDS PDF ♯ 41-0255).…”

“…All peaks identified at their corresponding binding energies are in well accordance with other literature reports. 10,20 The Cu:Ga:O atomic compositional (at%) of films annealed at 900 °C and 1000 °C were studied using XPS since these films displayed the presence of single-phase CuGaO 2 in XRD analysis. Near stoichiometric at% of Cu:Ga:O-24.05: 25.50: 50.46 was identified in films annealed at 900 °C.…”

“…), and oxygen is a negative divalent anion (O 2− ). 9 Among these oxide semiconductors, CuGaO 2 has become prominent due to its noteworthy optical, 10,11 electrical, 10,11 and photovoltaic properties. 12,13 It belongs to a family of p-type TCOs with a bandgap of 3.6 eV.…”

“…14,16 Due to their excellent properties, CuGaO 2 makes an outstanding candidate material for applications in solar cells, [17][18][19] photocatalysis, 8,20 electrolysis of water for oxygen, and hydrogen evolution for renewable energy. 12,21 Literature reports the synthesis of CuGaO 2 thin films using techniques such as pulsed laser deposition, 22,23 hydrothermal method, 12,20 sol-gel deposition, 10,24 and spin coating. 25 There are very few reports of CuGaO 2 thin films properties deposited using RF magnetron sputtering.…”

Synthesis, characterization and electrocatalytic properties of delafossite CuGaO2

“…8 The conductivity and electronic structures of delafossite (CuM III O 2 ) materials are reported in details elsewhere. 1,9 Delafossite CuGaO 2 demonstrates very interesting properties including optical, 9,10 electronic, 7,9,10 and photovoltaic properties. 2,3,11 CuGaO 2 nanoplates have been used as the photo-electrode materials in p-type dye sensitized solar cells to accelerate the photo-voltage and photocurrent.…”