MSc. Student, Universiti Sains Malaysia
Study of growth ZnO on Porous Silicon
An MSM photodetector based on these structures will develop later to test their performance as photodetectors.
Abstract: To improve productivity of a transistor that includes an oxide semiconductor and has good electrical characteristics. In a top-gate transistor including a gate insulating film and a gate electrode over an oxide semiconductor film, a metal film is formed over the oxide semiconductor film, oxygen is added to the metal film to form a metal oxide film, and the metal oxide film is used as a gate insulating film. After an oxide insulating film is formed over the oxide semiconductor film, a metal film may be formed over the oxide insulating film. Oxygen is added to the metal film to form a metal oxide film and added also to the oxide semiconductor film or the oxide insulating film.
Pub.: 07 Feb '17, Pinned: 29 Jul '17
Abstract: Provided is a transistor which includes an oxide semiconductor film and has stable electrical characteristics. In the transistor, over an oxide film which can release oxygen by being heated, a first oxide semiconductor film which can suppress oxygen release at least from the oxide film is formed. Over the first oxide semiconductor film, a second oxide semiconductor film is formed. With such a structure in which the oxide semiconductor films are stacked, the oxygen release from the oxide film can be suppressed at the time of the formation of the second oxide semiconductor film, and oxygen can be released from the oxide film in later-performed heat treatment. Thus, oxygen can pass through the first oxide semiconductor film to be favorably supplied to the second oxide semiconductor film. Oxygen supplied to the second oxide semiconductor film can suppress the generation of oxygen deficiency, resulting in stable electrical characteristics.
Pub.: 31 Jan '17, Pinned: 29 Jul '17
Abstract: In this article, temperature-dependent current-voltage characteristics of n-ZnO/p-Si nanoparticle thin film heterojunction diode grown by RF sputtering technique are analyzed in the temperature range of 300–433 k to investigate the performance of the device in high temperature environment. The microstructural, morphological, optical and temptrature dependent electrical properties of as-grown nanoparticle thin film were characterized by X-ray diffractometer (XRD), atomic force microscopy (AFM), field emmision scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), variable angle ellipsometer and semiconductor device analyzer. XRD spectra of as-grown ZnO films are exhibited that highly c-axis oriented ZnO nanostructures are grown on p- Si〈100〉 substrate whereas AFM and FESEM images confirm the homogeneous deposition of ZnO nanoparticles on surface of Si substratewith minimum roughness.The optical propertiesof as-grown ZnO nanoparticles have been measured in the spectral range of 300–800 nm using variable angle ellipsometer.To measure electrical parameters of the device prototype in the temperature range of room temperature (300 K) to 433 K, large area ohmic contacts were fabricated on both side of the ZnO/Si heterostructure. From the current-voltage charcteristics of ZnO/Si heterojunction device, it is observed that the device exhibits rectifing nature at room temperature. However, with increase in temperature, reverse saturation current and barrier height are found to increase, whereas ideality factor is started decreasing. This phenomenon confirms that barrier inhomogeneities are present at the interface of ZnO/Si heterojunction, as a result of lattice constant and thermal coefficient mismatch between Si and ZnO. Therefore, a modified value of Richardson constant [33.06 Acm−2K−2] has been extracted from the temperature-dependent electrical characteristics after assuming the Gaussian distribution of special barrier height inhomogeneities across the Si/ZnO interface which is close to its theoretical value [32 Acm−2K−2]. This result indicates that regardless of presence of barrier height inmogeneities, ZnO/Si heterojunction diode still hasability to perform well in high temperature environment.
Pub.: 22 Dec '16, Pinned: 29 Jul '17
Abstract: Well-aligned zinc oxide nanorod arrays (ZNAs) synthesized using chemical bath deposition were fabricated on a gallium-doped zinc oxide substrate, and the effects of varying the precursor concentrations on the growth and nanoscale electrical properties of the ZNAs were investigated. The as-synthesized ZNAs were characterized using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), conducting atomic force microscopy (CAFM), and scanning surface potential microscopy (SSPM). The FESEM and AFM images show that the growth rate in terms of length and diameter is highly sensitive to the precursor concentration. CAFM and SSPM analyses indicate that when concentrations of both the zinc acetate and hexamethylenetetramine solutions were 30 mM, the coverage percentages of the recordable and conducting regions on the ZNA surface were 48.3% and 0.9%, which is suitable for application in resistive random access memory devices.
Pub.: 06 Feb '17, Pinned: 29 Jul '17
Abstract: In this work, we have employed a simple and cheap chemical bath deposition method to prepare ZnO nanorod arrays (NRAs) and investigated their application as an antireflective layer in the polycrystalline silicon solar cells. The morphology and crystalline structure of the synthesized ZnO NRAs have been studied by scanning electron microscope, X-ray diffractometer, and high resolution transmission electron microscope. It is shown that the synthesized ZnO NRAs feature a perfect crystalline wurzite structure with a diameter of approximately 40–50 nm, and have a preferential growth along  direction. Moreover, it is demonstrated that the performance of the polycrystalline silicon solar cells using ZnO NRAs as an antireflective layer is much better than that of the solar cells using ZnO thin film as an antireflective layer or the solar cells without using any antireflective layer. Specifically, the photovoltaic conversion efficiency increases from 2.27% for the polycrystalline silicon solar cells without using any antireflective layer to 6.61% for the polycrystalline silicon solar cells using ZnO NRAs as an antireflective layer. This work is highly relevant to the development of an advanced process for the improvement of the performance of solar cells.
Pub.: 21 Dec '16, Pinned: 29 Jul '17
Abstract: Columnar mesoporous Si thin films and dense nanowire (SiNW) carpets were investigated by spectroscopic ellipsometry in the visible-near-infrared wavelength range. Porous Si layers were formed by electrochemical etching while structural anisotropy was controlled by the applied current. Layers of highly oriented SiNWs, with length up to 4.1 μm were synthesized by metal-assisted chemical etching. Ellipsometric spectra were fitted with different multi-layered, effective medium approximation-based (EMA) models. Isotropic, in-depth graded, anisotropic and hybrid EMA models were investigated with the help of the root mean square errors obtained from the fits. Ellipsometric-fitted layer thicknesses were also cross-checked by scanning electron microscopy showing an excellent agreement. Furthermore, in the case of mesoporous silicon, characterization also revealed that, at low current densities (<100 mA/cm2), in-depth inhomogeneity shows a more important feature in the ellipsometric spectra than anisotropy. On the other hand, at high current densities (>100 mA/cm2) this behavior turns around, and anisotropy becomes the dominant feature describing the spectra. Characterization of SiNW layers showed a very high geometrical anisotropy. However, the highest fitted geometrical anisotropy was obtained for the layer composed of ∼1 μm long SiNWs indicating that for thicker layers, collapse of the nanowires occurs.
Pub.: 10 Dec '16, Pinned: 29 Jul '17
Join Sparrho today to stay on top of science
Discover, organise and share research that matters to you