Abstract
Electrodeposition technique is employed to prepare cuprous oxide (Cu
2
O) thin film on fluorine-doped tin oxide (FTO) conducting glass substrate through the reduction of copper lactate in alkaline solution at pH = 12.25. Structural, optical and dielectric properties of the prepared film is investigated by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV–Visible absorbance, photoluminescence (PL) and broadband dielectric spectroscopy (BDS). The structural means (XRD, SEM and EDS) revealed the formation of self-assembled cubic microstructure of Cu
2
O with average grain size of around 1.5
μ
m. The UV–Vis absorbance spectrum gives optical band gap of 2.05 eV. The PL spectrums confirmed the presence of defect centers ascribed to various forms of oxygen
(
V
O
1
+
,
V
O
2
+
)
and copper (
V
Cu
1
+
) vacancies which are responsible for the conduction in the Cu
2
O film. The conduction mechanism in the Cu
2
O film is successfully described by the correlated barrier hopping (CBH) model in which bipolaron hopping become prominent. The density of defect states
N
, the effective barrier height
W
and the hopping distance
R
ω
are also calculated based on the CBH model. Two dielectric relaxation processes (
β
1
and
β
2
) with Arrhenius temperature dependence and activation energies of 0.31 and 0.48 eV are observed. The fast
β
2
-relaxation process with activation energy of 0.48 eV is attributed to the Maxwell–Wagner-Sillars (MWS) polarization while the slow
β
1
-relaxation process with activation energy of 0.31 eV is due to the hopping of the oxygen and copper vacancies.