Room Temperature Photoluminescence and Photoconductivity of Wet Chemical Deposited ZnO Nanowires Used for Solar Cells

oai:i-ETC.journals.isel.pt:article/11ZnO 1-D nanostructures (nanowires) were deposited by a two-step wet chemical process. The dimensions of wires were about 100 nm - 1100 nm in length and about 20 - 120 nm in diameter. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique was used to obtain the microstructural information from the films. The nanowire films were also characterized optically by transmittance measurement and room temperature photoluminescence (PL) measurements. The transport properties of the samples were characterized by performing transient photoconductivity (TPC) experiments

Study of trap states in zinc oxide (ZnO) thin films for electronic applications

The electrical properties of ZnO thin films grown by pulsed laser deposition were studied. Field-effect devices with a mobility reaching 1 cm2/V s show non-linearities both in the current–voltage and in the transfer characteristics which are explained as due to the presence of trap states. These traps cause a reversible threshold voltage shift as revealed by low-frequency capacitance–voltage measurements in metal insulator semiconductor (MIS) capacitors. Thermal detrapping experiments in heterojunctions confirm the presence of a trap state located at 0.32 eV

Room Temperature Photoluminescence and Photoconductivity of Wet Chemical Deposited ZnO Nanowires Used for Solar Cells

ZnO 1-D nanostructures (nanowires) were deposited by a two-step wet chemical process. The dimensions of wires were about 100 nm - 1100 nm in length and about 20 - 120 nm in diameter. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique was used to obtain the microstructural information from the films. The nanowire films were also characterized optically by transmittance measurement and room temperature photoluminescence (PL) measurements. The transport properties of the samples were characterized by performing transient photoconductivity (TPC) experiments

A Flexible Proximity Sensor Fully Fabricated by Inkjet Printing

A flexible proximity sensor fully fabricated by inkjet printing is proposed in this paper. The flexible proximity sensor is composed of a ZnO layer sandwiched in between a flexible aluminum sheet and a web-shaped top electrode layer. The flexible aluminum sheet serves as the bottom electrode. The material of the top electrode layer is nano silver. Both the ZnO and top electrode layers are deposited by inkjet printing. The fully inkjet printing process possesses the advantages of direct patterning and low-cost. It does not require photolithography and etching processes since the pattern is directly printed on the flexible aluminum sheet. The prototype demonstrates that the presented flexible sensor is sensitive to the human body. It may be applied to proximity sensing or thermal eradiation sensing

PII: S0378-7753(99)00435-8

Abstract Amorphous tin-oxide films were prepared by spray pyrolysis of SnCl P 2H O mixed with CH -COOH and deposited onto a stainless 2 2 3 Ž . Ž . steel substrate at mild temperatures 3508C . The films grown were characterized by X-ray photoelectron spectroscopy XPS and Ž . scanning electron microscopy with energy-dispersive X-ray analysis SEM-EDX . Also, they were tested as electrodes in lithium rechargeable batteries. The XPS results suggest that the substrate is thoroughly coated and that the films are composed mainly of SnO and SnO . These films exhibit good charge-discharge properties over more than 100 cycles. Heating at 6008C causes significant changes in 2 their surface composition, in the virtual disappearance of the tin component and in the presence of oxygen-bound Fe. Under these conditions, the reversible capacity dramatically fades and the cell behaves similarly to that made from uncoated substrate. q 2000 Elsevier Science S.A. All rights reserved

Photoconductivity Study of Sputter-Deposited Cu2OCu_2O Films

Cuprous oxide $(Cu_2O)$ thin films were deposited by radio frequency sputtering technique on fused silica substrates. The X-ray diffraction study of the $Cu_2O$ samples showed reflections from (111) and (200) planes of cubic $Cu_2O$. The samples were then annealed at 1008 K in nitrogen $(N_2)$ atmosphere. Annealed samples indicated strain relaxation. The samples were then characterized optically by measuring the transmittance using an ultraviolet-visible-near infrared photospectrometer. The band gap of the as-deposited samples were found to be ≈ 2.1 eV, whereas the annealed samples had a band gap of ≈ 2.6 eV. The transient photocurrent decay measurements of the annealed films indicated slow non-exponential power law decays in several time windows, indicating multiple trapping of the carriers in the deep defects within the band gap. The steady-state photo and dark current measurement and persistent photocurrent (PPC) was carried out on the annealed samples. In general, the photocurrent was found to be much smaller than the dark current. The steady-state and transient photocurrent measurements were utilized to determine the carrier lifetime-mobility product, 〈μτ 〉 of the samples and to determine the carrier mobility, 〈μ 〉