A plasma enhanced atomic layer deposition process has been demonstrated for Lanthanum oxide films using La (thd)3 precursor and oxygen plasma. The chemical and electrical properties of La2O3 ultra-thin films on Si (100) substrates before and after post-annealing in N2 ambient have been investigated. X-ray photoelectron spectroscopic revealed that interface reactions take place after annealing process which lead to oxygen insufficiency, as well as the balance band offset decreases with the increase of annealing temperature. The capacitance-voltage and current-voltage characteristics show La2O3 capacitors annealed at 900 °C have negligible hysteresis, smaller interface trap density in comparison with as-deposited samples, but larger flat band voltage and higher gate-leakage current density due to the appearance of oxygen vacancy in the La2O3 films.
AbstractCurrent-voltage characteristics of Au contacts formed on buried implanted oxide silicon-on-insulator structures and molecular beam epitaxially grown GaAs on (1012) sapphire and silicon-on-sapphire substrates indicate that the dominant transport mechanism in these films is space-charge-limited current conduction in the presence of deep-level states. The deep-level parameters, determined using an analysis of the current-voltage characteristics, appear to be sensitive to the nature of crystallographic defects present in the grown layers. Conduction in the GaAs film on SOS was dominated by one discrete state located ~ 0.28eV below the conduction band-edge, which is close to the El center uniquely observed in the molecular beam epitaxially grown GaAs-on-Si. Discrete levels are also observed in annealed buried implanted oxide silicon-on-insulator films. In contrast, the GaAs films deposited directly on (1012) sapphire substrates and rapid-thermally annealed high-dose As implanted buried oxide SOI films appear to have a continuous distribution of states. The distributed states in GaAs films deposited directly on sapphire probably arise from the electrical activity of the double-position boundaries present in this material system.
Modeling of Pd/ZnO Schottky diode has been performed together with a set of simulations to investigate its behavior in current-voltage characteristics. The diode was first fabricated and then the simulations were performed to match the IV curves to investigate the possible defects and their states in the bandgap. The doping concentration measured by capacitance-voltage is 3.4 x 1017 cm-3. The Schottky diode is simulated at room temperature and the effective barrier height is determined from current voltage characteristics both by measurements and simulations and it was found to be 0.68eV. The ideality factor obtained from simulated results is 1.06-2.04 which indicates that the transport mechanism is thermionic. It was found that the recombination current in the depletion region is responsible for deviation of experimental values from the ideal thermionic model deployed by the simulator.
ABSTRACTTo study the formation of ohmic contacts, several metals have been deposited on p-types ZnTe and ZnSe epitaxial layers. The metals were deposited on the layers either by simple evaporation or by electroplating. The current-voltage characteristics associated with each metal contact were measured. The preliminary results of these measurements indicate that electroplating is a better technique for making ohmic contact to these layers.
Heteroepitaxial n-ZnO films have been grown on commercial p-type 6H-SiC substrates by plasma-assisted molecular-beam epitaxy, and n-ZnO/p-SiC heterojunction mesa structures have been fabricated and their photoresponse properties have been studied. Current-voltage characteristics of the structures had a very good rectifying diode-like behavior with a leakage current less than 2 x 10-4 A/cm2 at -10 V, a breakdown voltage greater than 20 V, a forward turn on voltage of ∼5 V, and a forward current of ∼2 A/cm2 at 8 V. Photosensitivity of the diodes, when illuminated from ZnO side, was studied at room temperature and photoresponsivity of as high as 0.045 A/W at -7.5 V reverse bias was observed for photon energies higher than 3.0 eV.
We investigated the influence of the In0.17Ga0.83N:Mg contact layer grown by plasma assisted molecular beam epitaxy on the resistivity of p-type Ni/Au contacts. We demonstrate that the Schottky barrier width for p-type contact is less than 5 nm. We compare circular transmission line measurements with a p-n diode current-voltage characteristics and show that discrepancies between these two methods can occur if surface quality is deteriorated. It is found that the most efficient contacts to p-type material consist of In0.17Ga0.83N:Mg contact layer with Mg doping level as high as 2 × 1020 cm–3.
This paper investigates the effect of soft X-ray irradiation various energy and times on P-N junction diodes. X-ray energy irradiated on P-N junction diode with 55 and 70 keV with various time in the range 5-50 sec. After irradiations were study on the current-voltage (I-V) characteristics and capacitance-voltage (C-V) characteristics. Leakages current after irradiated by X-ray are not change, while forward current are increase about 3 orders. The change of current-voltage characteristics can analyze by many parameter such as carrier lifetime and series resistance. Capacitance-voltage characteristics after irradiation are not change. The results show that soft X-ray technique can be improving performance of the P-N junction diodes. These techniques are importance to use for improving device performance in industry work.
Study of the current-voltage characteristics of n-on-p junction fabricated by pr oton-implanted molecular beam epitaxial Hg1-xCdxTe