A. Sreedhar

Process-Parameter-Dependent Structural, Electrical, and Optical Properties of Reactive Magnetron Sputtered Ag-Cu-O Films

Silver-copper-oxide thin films were formed by RF magnetron sputtering technique using Ag80Cu20 target at various oxygen partial pressures in the range 5 × 10−3–8 ×10−2 Pa and substrate temperatures in the range 303–523 K. The effect of oxygen partial pressure and substrate temperature on the structure and surface morphology and electrical and optical properties of the films were studied. The Ag-Cu-O films formed at room temperature (303 K) and at low oxygen partial pressure of 5 × 10−3 Pa were mixed phase of Ag2Cu2O3 and Ag, while those deposited at 2 × 10−2 Pa were composed of Ag2Cu2O4 and Ag2Cu2O3 phases. The crystallinity of the films formed at oxygen partial pressure of 2 × 10−2 Pa increased with the increase of substrate temperature from 303 to 423 K. Further increase of substrate temperature to 523 K, the films were decomposed in to Ag2O and Ag phases. The electrical resistivity of the films decreased from 0.8 Ωcm with the increase of substrate temperature from 303 to 473 K due to improvement in the crystallinity of the phase. The optical band gap of the Ag-Cu-O films increased from 1.47 to 1.83 eV with the increase of substrate temperature from 303 to 473 K.

Electrical and optical properties of molybdenum doped zinc oxide films prepared by reactive RF magnetron sputtering

Molybdenum doped zinc oxide (MZO) films were deposited on to glass substrates held at temperatures in the range from 303 to 673 K by reactive RF magnetron sputtering method. The chemical composition, crystallographic structure and surface morphology, electrical and optical properties of the films were determined. The films contained the molybdenum of 2.7 at. % in ZnO. The films deposited at 303 K were of X-ray amorphous. The films formed at 473 K were of nanocrystalline in nature with wurtzite structure. The crystallite size of the films was increased with the increase of substrate temperature. The optical transmittance of the films was in the visible range was 80–85%. The molybdenum (2.7 at %) doped zinc oxide films deposited at substrate temperature of 573 K were of nanocrystalline with electrical resistivity of 7.2×10−3 Ωcm, optical transmittance of 85 %, optical band gap of 3.35 eV and figure of merit 30.6 Ω−1cm−1.

Substrate Bias Influenced Physical Characteristics of Nanocrystalline Silver Copper Oxide Films

The silver-copper-oxide (Ag2Cu2O3) films were prepared by reactive magnetron sputtering of equimolar silver copper alloy target (Ag50Cu50) onto the glass substrates in an oxygen partial pressure of 2 × 10−2 Pa and at different substrate bias voltages in the range from 0 to −90 V. The X-ray photoelectron spectroscopic studies on the films formed at substrate bias voltage of −60 V showed the characteristic core level binding energies of Ag2Cu2O3. The films formed on unbiased substrates were X-ray amorphous. The mixed phase films of Ag2Cu2O3 and Ag were deposited at substrate bias voltage of −30 V, where as nanocrystalline and single phase Ag2Cu2O3 films were achieved at substrate bias voltage of −60 V. The atomic force micrographs of the unbiased films showed spherical shaped grains while those deposited at higher substrate bias voltages exhibited grains with pyramidal shape. The electrical resistivity of the films increased from 1.2 × 10−5 to 8.6 × 10−3 Ωcm with increase of substrate bias voltage from 0 to −60 V respectively. The optical band gap of the films increased from 1.78 to 1.92 eV with increase of substrate bias voltage from 0 to −60 V.

Sputter Power Influenced Structural, Electrical, and Optical Behaviour of Nanocrystalline CuNiO2 Films Formed by RF Magnetron Sputtering

Copper nickel oxide (CuNiO2) films were deposited on glass and silicon substrates using RF magnetron sputtering of equimolar Cu50Ni50 alloy target at different sputter powers in the range of 3.1–6.1 W/cm2. The effect of sputter power on the chemical composition, crystallographic structure, chemical binding configuration, surface morphology, and electrical and optical properties of CuNiO2 films was investigated. The films formed at sputter power of 5.1 W/cm2 were of nearly stoichiometric CuNiO2. Fourier transform infrared spectroscopic studies indicated the presence of the characteristic vibrational bands of copper nickel oxide. The nanocrystalline CuNiO2 films were formed with the increase in grain size from 75 to 120 nm as the sputter power increased from 3.1 to 5.1 W/cm2. The stoichiometric CuNiO2 films formed at sputter power of 5.1 W/cm2 exhibited electrical resistivity of 27 Ωcm, Hall mobility of 21 cm2/Vsec, and optical bandgap of 1.93 eV.

Structural, Electrical, and Optical Properties of Reactively Sputtered Ag-Cu-O Films

Thin films of silver-copper-oxide were deposited on glass substrates by RF magnetron sputtering of Ag80Cu20 target under various oxygen partial pressures in the range 5×10−3–8×10−2 Pa. The effect of oxygen partial pressure on the crystallographic structure and surface morphology and electrical and optical properties was systematically studied and the results were reported. The oxygen content in the films was correlated with the oxygen partial pressure maintained during the growth of the films. The films which formed at low oxygen partial pressure of 5×10−3 Pa were mixed in phase of Ag2Cu2O3 and Ag while those deposited at 2×10−2 Pa were grown with Ag2Cu2O3 and Ag2Cu2O4 phases. The films which formed at oxygen partial pressure of 2×10−2 Pa showed electrical resistivity of 2.3 Ωcm and optical band gap of 1.47 eV.

Oxygen Partial Pressure Influenced Structural, Morphological and Optical Properties of Nanocrystalline ZnO Thin Films Formed by RF Magnetron Sputtering

Zinc oxide (ZnO) thin films were deposited by RF magnetron sputtering on silicon (100) and glass substrates held at room temperature by varying the oxygen partial pressures in the range 5×10−3 Pa‐ 5×10−2 Pa.. The deposition rate of the films decreased from 5.8 to 2.5 nm/min with increase of oxygen partial pressure from 5×10−3 to 5×10−2 Pa. The content of oxygen in the films are correlated with the oxygen prevailed in the sputter chamber. The films formed at oxygen partial pressure 5×10−3 Pa showed (100), (002) and (110) reflections indicated the growth of polycrystalline ZnO films. Further increase of oxygen partial pressure to 2×10−2 Pa the intensity of (100) reflection increased and then decreased with increase of oxygen partial pressure to 5×10−2 Pa. The crystallite size of ZnO thin films increased from 15.0 nm to 21.8 nm and then decreased to 13.0 nm with increase of oxygen partial pressure from 5×10−3 to 5×10−2 Pa. The optical absorption band edge shifted towards lower wavelength side with increase o...