A comparative investigation on growth, nanostructure and electrical properties of copper oxide thin films as a functionof annealing conditions

This paper is an attempt to compare the influenceof various annealing conditions on growth, nanostructure,surface morphology and electrical properties ofcopper oxide thin films. Cu thin films of 85 nm thicknesswere deposited on glass substrate by thermal evaporationmethod, and then post-annealed at different environments(air and oxygen flow), different temperatures (200–400 ̊ C)and different times (35 and 75 min). X-ray diffractionresults showed (Cu(2)O) cuprite phase for all annealedsamples at 200 and 250 ̊ C and (CuO) tenorite phase for allsamples annealed under different conditions at 350 and400 ̊ C. A complex phase of CuO and Cu(2)O was observedfor all annealed samples at 300 ̊ C, with exception for thesample annealed with flow of oxygen for 75 min. Theatomic force microscopy results showed that surface morphologyof the samples was strongly affected by thechanges of annealing conditions (i.e., time, temperatureand environment). The size of the grains increased withannealing temperature and time, while the samplesannealed with oxygen flow showed larger grains than thoseannealed in air. Two different behaviors with annealingtemperature were distinguished for the surface roughnessof the samples annealed in the air and those annealed withflow of oxygen. Resistivity and Hall effect of samples weremeasured by a four-point probe instrument and a Halleffect investigation system, respectively. The electricalanalyses showed that the variations in annealing conditionshad a remarkable effect on measured electrical parameters,namely films resistivity, carriers concentration and type,and Hall mobility.