M. Hari Prasad Reddy

Characterization of Silver Oxide Films Formed by Reactive RF Sputtering at Different Substrate Temperatures

Silver oxide (A2O) films were deposited on glass and silicon substrates held at temperatures in the range 303–473 K by reactive RF magnetron sputtering of silver target. The films formed at room temperature were single phase Ag2O with polycrystalline in nature, while those deposited at 373 K were improved in the crystallinity. The films deposited at 423 K were mixed phase of Ag2O and Ag. Atomic force micrographs of the films formed at room temperature were of spherical shape grains with size of 85 nm, whereas those deposited at 473 K were with enhanced grain size of 215 nm with pyramidal shape. Electrical resistivity of the single phase films formed at room temperature was 5.2 × 10−3 Ωcm and that of mixed phase was 4.2 × 10−4 Ωcm. Optical band gap of single phase films increased from 2.05 to 2.13 eV with the increase of substrate temperature from 303 to 373 K, while in mixed phase films it was 1.92 eV.

Effect of substrate temperature on the structural, electrical and optical behaviour of reactively sputtered Ag–Cu–O films

Thin films of Ag–Cu–O were deposited on glass substrates by radio frequency magnetron sputtering of an Ag70Cu30 target at an oxygen partial pressure of 2×10−2 Pa, a sputter pressure of 4 Pa and at different substrate temperatures in the range 303–548 K. The deposited films were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, atomic force microscopy, ultraviolet–visible–infrared spectroscopy and four-probe techniques. The effect of substrate temperature on the core-level binding energies, crystallographic structure, surface morphology and electrical and optical properties of the deposited films was systematically studied. The films formed at room temperature (303 K) showed a core-level binding energy of Ag 3d5/2 of 367.9 eV due to the growth of single-phase Ag2Cu2O3 films, whereas those deposited at 523 K exhibited a lower energy value of 367.2 eV due to the presence of silver, silver oxides and copper oxide. The films formed at room temperature were nanocrystalline Ag2Cu2O3. The substrate temperature induced growth of a mixed phase of Ag2Cu2O3 and Ag2Cu2O4 in the temperature range 348–473 K. At higher temperatures the films were decomposed into silver and silver oxide. The electrical resistivity of the films decreased from 8.2 to 0.6 Ω cm with an increase in substrate temperature from 303 to 548 K due to an improvement in crystallinity and structural changes in the films. The optical band gap of the Ag–Cu–O films increased from 1.95 to 2.15 eV with an increase in substrate temperature from 303 to 523 K, whereas at a higher temperature of 548 K it decreased to 2.11 eV.

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.

Structural, Electrical and Optical Behaviour of RF Magnetron Sputtered Nanocrystalline Silver Oxide Films: Bias Effect

Nanocrystalline silver oxide thin films were deposited on glass substrates by RF magnetron sputtering of metallic silver target in an oxygen partial pressure of 2×10−2 Pa and at sputtering pressure of 4 Pa under different substrate bias voltages in the range from 0 to −60 V. Influence of bias voltage on the structure, morphological, electrical and optical properties of the silver oxide films was investigated. The unbiased films formed at room temperature showed the presence of (111) reflection of Ag2O. The films formed at substrate bias voltage of −30 V showed a strong (111) texture with large sized grains of Ag2O. At higher substrate voltage of −60 V the films showed a mixed phase of Ag2O and Ag. The crystallite size of the films increased from 5.3 to 18.2 nm with increase of substrate bias voltage from 0 to −30 V. The grain size of the films increased from 71 to 230 nm with the increase of substrate bias voltage from 0 to −30 V. The electrical resistivity of the Ag2O films decreased remarkably with increase of substrate bias voltage to −30 V. At an optimum substrate bias voltage of −30 V, the Ag2O films were nanocrystalline with electrical resistivity of 1.2×10−3 Ωcm and optical band gap of 2.20 eV.Nanocrystalline silver oxide thin films were deposited on glass substrates by RF magnetron sputtering of metallic silver target in an oxygen partial pressure of 2×10−2 Pa and at sputtering pressure of 4 Pa under different substrate bias voltages in the range from 0 to −60 V. Influence of bias voltage on the structure, morphological, electrical and optical properties of the silver oxide films was investigated. The unbiased films formed at room temperature showed the presence of (111) reflection of Ag2O. The films formed at substrate bias voltage of −30 V showed a strong (111) texture with large sized grains of Ag2O. At higher substrate voltage of −60 V the films showed a mixed phase of Ag2O and Ag. The crystallite size of the films increased from 5.3 to 18.2 nm with increase of substrate bias voltage from 0 to −30 V. The grain size of the films increased from 71 to 230 nm with the increase of substrate bias voltage from 0 to −30 V. The electrical resistivity of the Ag2O films decreased remarkably with incr...

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.

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...