الفهرس 
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Abstract
Abstract
Transparent conducting oxides (TCO) are materials with high electrical conductivities and low optical absorptions for the visible light. Thin films of TCO used as transparent electrodes in technological applications including photovoltaic cells, flat panel displays and light emitting diodes. The used TCO in electronic devices such as indium tin oxide (ITO), fluorine doped tin oxide (FTO), zinc oxide (ZnO) are n-type, while p-type TCO are not largely commercially available and have limitations in stability and material synthesis. Development of p-type TCO will open up application possibilities that are simply not feasible with n-type materials alone, such as transparent diodes, transistors and p–n heterojunctions.
Cu- based oxide is an interesting family of materials for these applications because of their p-type semi-conducting. However, p-type copper-based delafossite materials, such as CuCrO2, CuAlO2, CuGaO2 and CuFeO2, have attracted significant interest due to their exceptional thermoelectric, magnetic and optical properties finding diverse technological applications in the fields of optoelectronic devices such as light emitting diodes, laser diodes, solar cells, functional windows and thermoelectric materials.
Overall, copper iron oxide (CFO) is the most attractive candidate among this class of materials because it is known to possess low treatment temperature, the highest electrical conductivity at room temperature. In addition, the material sources are nontoxic, abundant and low cost. CFO is naturally display p-type conduction, high chemical stability, good crystallinity and optical energy gap Eg about 1.5 eV.
This work will focus on the development of p-type CFO films for optoelectronic applications by use chemical spray pyrolysis technique (CSPT) which is advantage on other deposition techniques by low equipment cost, simple and safe technique, non-vacuum requirement, low temperature processing and the possibility of large area deposition. The structure, optical and electrical characterization of the prepared samples will be study in order to understand their fundamental properties. The proposal will open the pathway toward the realization of p-type transparent oxide thin films that can utilized to fabricate p-n junction with good efficiency and low manufacturing cost.
In recent thesis, the effect of various parameters such as: spray solution quantity (SSQ), annealing temperature (TA), Fe/(Cu+Fe) ratio in spray solution, doping with elements tin (Sn) and indium (In) on structural, optical and electrical properties were studied. X- ray diffraction (XRD) analysis shows that CFO films as deposited were amorphous structure, hence the annealing process is vital step to determine delafossite phase, the ideal annealing parameters found to be TA=850ºC in nitrogen gas (N2) for 2 hour. Films annealed at TA=850ºC show single phase, polycrystalline with rhombohedral structure and (012) preferred orientation. Cu, Fe, and O have atomic concentration 1:1:2. The optical transmission values vary between 30-70% in VIS-IR region, optical band gap range 1.88 -1.48 eV. The electrical conductivity increase from 9 Х 10-5 to 1.5 Х 10-1 S/cm, the carrier density increase from 5.5 Х 1014 to 7.4 Х 1018 , the Hall mobility value μ ≤ 1 cm2/V·s and all films are p-type conductivity.
The change of iron concentration (Fe/ Fe+Cu) in the spray solution x= 0.47, 0.49, 0.51, 0.53 show the appearance of impurities phase, while film deposited at x=0.5 show single delafossite phase this is the ideal value.
The CFO doped Sn films show delafossite structure with appearance of impurity peaks. Films have high transmittance (T) 40-80 % and reflectance (R) 5-20 % in VIS-IR, the Eg values found to ~ 1.74 eV. The Seebeck coefficients have positive sign confirmed CFO:Sn (0.03) sample is p-type material. The resistivity (ρ) decrease from 1.1 Х104 Ω.cm for pure CFO to 1.6 Х102 Ω.cm for x=0.03, the hole concentration increased up to 1.06 Х1017 cm-3.
Films doped with In maintain the delafossite structure no impurity peaks detected. The optical transmittance increase by doping (T) 40-75 % and (R) 5-10 % in VIS-IR, The Eg values found to be 1.6 eV -2.3 eV. The Seebeck coefficients positive sign confirmed CuFe1-xInxO2 (0.03) sample is p-type material. The conductivity increase one order up to 1Х10-1 S/cm, the hole concentration P= 3 Х1018 cm-3 at In concentration x=0.03.
This work report the first successfully fabricated of p-n junction by using pure and doped CFO film as p-layer. The Ag/p-CuFeO2/ n-ITO, Ag/p-CFO:Sn/ n-ITO and Ag/p-CFO:In/ n-ITO junction devices were successfully fabricated and tested, the I-V curve shows the rectifier behavior. The rectifying ratio (RR(v)) found to be 2.6 and 3, while the ideality factor value (n) ~ 11.
Keywords: Copper iron oxide; delafossite; chemical spray pyrolysis; structural study; optical properties;hall effect measurment;p-n junction.