Search results for "Optoelectronics"

Fabrication and characterization of chromium based single-electron transistors with evaporated chromium oxide barrier tunnel junctions

1999

We fabricated chromium based single-electron transistors comprising small-area Cr/CrOx/Cr tunnel junctions with an evaporated chromium oxide barrier. The transistors are fabricated using e-beam lithography with a bilayer resist and two-angle shadow evaporation. We describe the fabrication process and discuss the device characteristics.

Normal Metal-Insulator-Superconductor Tunnel Junctions With Pulsed Laser Deposited Titanium Nitride as Superconductor

2021

Here we report the fabrication of normal metal – insulator – superconductor (NIS) tunnel junctions using superconducting titanium nitride grown by pulsed laser deposition (PLD). The films for NIS junction fabrication were deposited on two different substrates: silicon nitride film and magnesium oxide. TiN films were characterized by means of electrical transport measurements, and films with superconducting transition temperatures above the liquid helium boiling point were chosen for fabrication of NIS junctions. Tunnel junction devices were successfully fabricated using electron beam lithography and shadow evaporation techniques. The insulator layer formation was performed using two differe…

Vacuum deposited perovskite solar cells employing dopant-free triazatruxene as the hole transport material

2017

Abstract Planar perovskite solar cells using organic charge selective contacts were fabricated. In a vacuum deposited perovskite-based solar cell, dopant and additive free triazatruxene as the hole transport layer was introduced for device fabrication. High open-circuit voltage of 1090 mV was obtained using methylammonium lead iodide (Eg=1.55 eV) as light harvesting material, thus representing a loss of only 460 mV which is in close vicinity of mature silicon technology (400 mV). The devices showed a very competitive photovoltaic performance, monochromatic incident photon-to-electron conversion efficiency of 80% and the power conversion efficiencies in excess of 15% were measured with a neg…

Fabrication and Characterization of Double- and Single-Clamped CuO Nanowire Based Nanoelectromechanical Switches

2021

Electrostatically actuated nanoelectromechanical (NEM) switches hold promise for operation with sharply defined ON/OFF states, high ON/OFF current ratio, low OFF state power consumption, and a compact design. The present challenge for the development of nanoelectromechanical system (NEMS) technology is fabrication of single nanowire based NEM switches. In this work, we demonstrate the first application of CuO nanowires as NEM switch active elements. We develop bottom-up and top-down approaches for NEM switch fabrication, such as CuO nanowire synthesis, lithography, etching, dielectrophoretic alignment of nanowires on electrodes, and nanomanipulations for building devices that are suitable f…

Charge Transport in Trap-Sensitized Infrared PbS Quantum-Dot-Based Photoconductors: Pros and Cons

2018

Control of quantum-dot (QD) surface chemistry offers a direct approach for the tuning of charge-carrier dynamics in photoconductors based on strongly coupled QD solids. We investigate the effects of altering the surface chemistry of PbS QDs in such QD solids via ligand exchange using 3-mercaptopropionic acid (MPA) and tetrabutylammonium iodide (TBAI). The roll-to-roll compatible doctor-blade technique was used for the fabrication of the QD solid films as the photoactive component in photoconductors and field-effect phototransistors. The ligand exchange of the QD solid film with MPA yields superior device performance with higher photosensitivity and detectivity, which is due to less dark cur…

Solution-processible electrode materials for a heat-sensitive piezoelectric thin-film sensor

2012

Abstract Piezoelectric sensors are needed in a wide range of applications from physiological measurement applications to industrial monitoring systems. Custom-designed, highly integratable and cost-effective sensor elements can be manufactured by using flexible materials in combination with high-throughput printing for fabrication. This would also enable the embedding of ubiquitous sensors in our living environment to improve the common welfare. Here, we have fabricated flexible piezoelectric sensor elements using printing methods. We demonstrated that alternative, printable electrode materials are compatible with temperature-sensitive functional substrates. Low-temperature curable electrod…

A Zone-Casting Technique for Device Fabrication of Field-Effect Transistors Based on Discotic Hexa-peri-hexabenzocoronene

2005

Fabrication and characterization of small tunnel junctions through a thin dielectric membrane

1998

We show that a small tapered hole through a thin silicon nitride membrane provides a mask for tunnel junction structures. Our experiments imply, unlike in the conventional planar electron beam lithography, that tunnel junctions are well voltage biased in this structure with vanishingly small on-chip impedance. Our technique allows fabrication of double junctions, and even multijunction linear arrays, with small metallic islands in between.

Optical Spectra and Direct Optical Transitions in Amorphous and Crystalline ZnO Thin Films and Powders

2010

Comparative studies of ZnO crystalline and amorphous thin films and nanocrystalline powders are reported. The UV-visible optical spectra were analyzed with special attention paid to the direct optical bandgap. Atmospheric radio-frequency barrier torch discharge and pulsed hollow cathode sputtering techniques for the film fabrication were used. For the crystalline films, similar values of the direct optical bandgap were found independent of the growth method used. The analysis of the amorphous films and powders revealed a pronounced Urbach-like exponential absorption tail approaching the bandedge. For the powders, the bandgap energies were larger than those for the crystalline and amorphous …

Particle Detectors made of High Resistivity Czochralski Grown Silicon

2004

We describe the fabrication process of fullsize silicon microstrip detectors processed on silicon wafers grown by magnetic Czochralski method. Defect analysis by DLTS spectroscopy as well as minority carrier lifetime measurements by µPCD method are presented. The electrical and detection properties of the Czochralski silicon detectors are comparable to those of leading commercial detector manufacturers. The radiation hardness of the Czochralski silicon detectors was proved to be superior to the devices made of traditional Float Zone silicon material.