Technological Background and Properties of Thin Film Semiconductors

Especially with the development of nanotechnology and polymer science, interest in research and production of both efficient and lower-cost semiconductor thin film materials is increasing day by day. The use of nano-structured thin films for efficient use of solar cells in production of n-type semiconductor materials is one of the most important sources of energy and new-generation energy. Considering the indicated trends and energy requirements, it has been important to transfer this technology in detail regarding the surface technologies related to the semiconductor materials produced with thin film technologies instead of bulk materials. With this aim, this book chapter “Technological Background and Properties of Thin Film Semiconductors” includes a brief story about semiconductors, band gap theory, thin film applications, and besides traditional thin film processing methods finally a new technology called aerosol deposition technique which allows room temperature processing of several materials for semiconductor applications, respectively. It is thought that it will make important contributions to the relevant field and bring a new perspective and direct scientific research in “process-structure–property-performance” relation

Comparison of processing parameter effects during magnetron sputtering and electrochemical anodization of TiO2 nanotubes on ITO/glass and glass substrates

Titanium thin films were deposited on glass and indium tin oxide (ITO) coated glass substrates by radio-frequency (RF) magnetron sputtering under varying sputtering parameters as: power, pressure, substrate temperature and target-substrate distance. The crystalline structure, crystallite size and texture coefficients of the films were evaluated in detail. As the evaluation points out, 100 W, 1.33 Pa ambient temperature and 70 mm were determined as the optimum sputtering parameters for intended crystalline structures. Subsequently, electrochemical anodization experiments were performed via varied electrolytes and under various anodization parameters (voltage, time and electrolyte type) in a twoelectrode electrochemical cell using the films obtained through the optimized sputtering parameters. The anodized samples were annealed at 450 degrees C for 1 h in air in order to obtain anatase transformation and the desired crystalline structure. The surface morphologies and the crystalline structures of the anodized films were evaluated through x-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. Finally, the anodization parameters for the formation of TiO2 nanotube arrays were determined as: 35 V and 35 min. in an electrolyte composed of 0.3 wt.-% NH4F - 2 wt.-% water - ethylene glycol

Comparison of processing parameter effects during magnetron sputtering and electrochemical anodization of TiO 2

Titanium thin films were deposited on glass and indium tin oxide (ITO) coated glass substrates by radio-frequency (RF) magnetron sputtering under varying sputtering parameters as: power, pressure, substrate temperature and target-substrate distance. The crystalline structure, crystallite size and texture coefficients of the films were evaluated in detail. As the evaluation points out, 100 W, 1.33 Pa ambient temperature and 70 mm were determined as the optimum sputtering parameters for intended crystalline structures. Subsequently, electrochemical anodization experiments were performed via varied electrolytes and under various anodization parameters (voltage, time and electrolyte type) in a twoelectrode electrochemical cell using the films obtained through the optimized sputtering parameters. The anodized samples were annealed at 450 degrees C for 1 h in air in order to obtain anatase transformation and the desired crystalline structure. The surface morphologies and the crystalline structures of the anodized films were evaluated through x-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. Finally, the anodization parameters for the formation of TiO2 nanotube arrays were determined as: 35 V and 35 min. in an electrolyte composed of 0.3 wt.-% NH4F - 2 wt.-% water - ethylene glycol

Electrical resistivity reduction and spatial homogenization of Ga-doped ZnO film by Zn layer insertion

Ga-doped ZnO (GZO) films inserted with a Zn layer were deposited at room temperature by a sputtering method to decrease carrier-compensating defects. The Zn-inserted GZO films showed a resistivity decrease resulting from an increase in carrier density. The carrier density further increased by thermal annealing and showed a maximum at around 400 degrees C. The formation of a SiO2 capping layer on the film surfaces enhanced the carrier density at temperatures higher than 400 degrees C, resulting in a lowered resistivity to 3.3 x 10(-4) Omega cm for a 200-nm-thick film. In addition, resistivity degradation that was induced at the erosion position in the sputtering deposition process disappeared. The increase in carrier density, decrease in resistivity, and homogenization of the electrical property indicate that carrier-compensating crystalline defects such as the zinc vacancy induced in Ga-doped ZnO films during the deposition process are decreased by the Zn enrichment