Temperature/Doping-Dependency of the Electrical Properties of the Nickel Doped Copper Oxide Thin Films

The electrical properties of the Nickel doped cupric oxide Ni-CuO thin films with various doping concentrations of Ni (0, 20, 30, 70, and 80%) are investigated at two different annealing temperatures; 200 and 400 °C. The electrical properties of the films; namely thermal activation energy and electrical energy gap are calculated and compared. We find that for the non-annealed Ni-CuO films, both thermal activation energy and electrical energy gap are decreased by increasing the doping concentration, while for the annealed films, the increase in the Ni doping results in the increase in thermal activation energy and electrical energy gap for most of the Ni-CuO films. We also observe that for a particular concentration, the annealing at 200 °C produces lower thermal activation energy and electrical energy gap than the annealing at 400 °C. We obtained two values of the activation energy varying from -5.52 to -0.51 eV and from 0.49 to 3.36 eV, respectively, for the annealing at 200 and 400 °C. We also obtained two values of the electrical bandgap varying from -11.05 to -1.03 eV and from 0.97 to 6.71 eV, respectively, for the annealing at 200 and 400 °C. It is also noticeable that the increase in the doping concentration reduces the activation energy, and hence the electrical bandgap energies.

Conductance Tunable Suspended Graphene Nanomesh by Helium Ion Beam Milling

This paper demonstrates that the electrical properties of suspended graphene nanomesh (GNM) can be tuned by systematically changing the porosity with helium ion beam milling (HIBM). The porosity of the GNM is well-controlled by defining the pitch of the periodic nanopores. The defective region surrounding the individual nanopores after HIBM, which limits the minimum pitch achievable between nanopores for a certain dose, is investigated and reported. The exponential relationship between the thermal activation energy (EA) and the porosity is found in the GNM devices. Good EA tuneability observed from the GNMs provides a new approach to the transport gap engineering beyond the conventional nanoribbon method.

X- ray diffraction and dielectric properties of PbSe thin films

Lead selenide PbSe thin films of different thicknesses (300, 500, and 700 nm) were deposited under vacuum using thermal evaporation method on glass substrates. X-ray diffraction measurements showed that increasing of thickness lead to well crystallize the prepared samples, such that the crystallite size increases while the dislocation density decreases with thickness increasing. A.C conductivity, dielectric constants, and loss tangent are studied as function to thickness, frequency (10kHz-10MHz) and temperatures (293K-493K). The conductivity measurements confirm confirmed that hopping is the mechanism responsible for the conduction process. Increasing of thickness decreases the thermal activation energy estimated from Arhinus equation is found to decrease with thickness increasing. The increase of thickness lead to reduce the polarizability α while the increasing of temperature lead to increase α.

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

Effects of Ga Content on Optical and Scintillation Properties in Ce3+-Doped YGd2(Al,Ga)5O12 Scintillators

The optical and scintillation properties of Ce3+-doped YGd2(Al,Ga)5O12 single crystal scintillators were investigated. The Ce3+ 5d-4f emission was blue-shifted with increasing Ga content due to the decrease of the crystal field strength. Temperature dependence of the photoluminescence decay times was measured and the thermal activation energy for the luminescence quenching was calculated. Light yield (LY) and its dependence on an integration time were measured under γ-ray excitation. The fast component content in the scintillation response increases with increasing Ga content. The YGd2Al2Ga3O12:Ce sample showed a high LY of 38,000 photons/MeV. The decrease of LY value observed for a YGd2Al1Ga4O12:Ce sample is mainly due to the thermal ionization of the 5d1 excited state of the Ce3+ emission center to the conduction band.