Papers by Keyword: Conductance

Abstract: Cadmium sulphide nanocrystallites have been synthesized using precipitation method. The average sizes of the prepared samples is determined by XRD (x-ray diffraction) method. Morphological studies are carried out by SEM (scanning electron microscopy) measurement. Necesssary elements present in prepared samples, are confirmed by EDAX (energy dispersive analysis of x-ray spectroscopy) method. By Ultraviolet visible spectroscopy measurement, the value of absorption wavelength, band gap values are calculated in optical method. The electrical properties are analysed using impedance analyser measurement for the Nanocrystallites.

Abstract: A thickness of Ba-introduced gate oxide was controlled with the oxygen concentration and a barrier layer thickness at a post-deposition annealing. The oxidation rate becomes slower with the low oxygen concentration and the thick barrier layer, and the thin oxide of 12 nm was realized with O₂ 5% and 9 nm of the barrier layer. This Ba-introduced thin gate oxide resulted in the field effect mobility of 13 cm²/Vs and the interface state density of 2×10¹¹ cm^-2eV^-1 at 0.25 eV below the conduction band edge of 4H-SiC.

Abstract: A correlation between field effect mobility and an accumulation conductance has been investigated at 4H-SiC MOS interface with barium. 4H-SiC n-channel MOSFETs and n-type MOS capacitors were fabricated with a barium-introduced SiO₂ and a conventional dry SiO₂. The field effect mobility was enhanced by introducing the barium-introduced SiO₂. It is found that there is a linear correlation between the mobility and the accumulation conductance. The MOS interface of the barium-introduced SiO₂ had a lower interface state density of 2×10¹¹ cm^-2eV^-1 than that of the conventional dry SiO₂.

Abstract: In this work we have investigated the frequency and the bias voltage dependence of the electrical responses of organic structures based on poly (triarylamine) (PTAA) thin film using ITO/Organic/Al diode structure. The frequency-dependent and bias voltage-dependent conductance and capacitance were investigated using a precision LCR meter with wide frequency test (10 Hz – 100 kHz) and various bias voltages ranges (0.2 to 5.0 V), respectively. Investigation revealed that conductance was strongly dependent on the frequency and bias voltage-dependent. Conductance was inversely proportional to the capacitance among the frequency. Meanwhile, the capacitance and series resistance were dependent until a certain value at the low frequency region, but the capacitance and series resistance were independent at high frequencies.

Abstract: In this study, electrical properties of MOS capacitors with varying oxide thicknesses have been investigated. The oxide growth was performed at 1050 °C without any further post-oxidation annealing steps resulting in oxide thicknesses between 2 nm and 32 nm. Capacitance-Voltage measurements revealed a decreasing density of interface defects for increasing oxide thickness suggesting a deterioration of the interface at the initial stage of the growth.

Abstract: Electrical properties of the gate oxides thermally grown in N₂O on n-type and p-type 4H-SiC have been compared using conventional MOS structure and inversion-channel MOS structure, respectively. Sufficient difference in the electrical properties of the gate oxides grown on n-type and p-type 4H-SiC was revealed. We conclude that the gate oxide process optimisation using inversion-channel MOS devices is superior as compared to the conventional MOS structure.

Abstract: In this thesis, aperiodic genomic DNA have weak charge transfer; the transmission coefficient of DNA with short period sequence does not seem to depend on the length, yet differently, the transmission pattern of aperiodic genomic DNA sequences strongly depends on the strand length. As the number of corresponding bases increases, fewer states will present good transmission ability, because aperiodic increasing bases make more backscattering; at low temperature, the transmission spectrum presents a higher number of transmitting states, due to a breaking of level degeneracy. At higher temperature, the number of transmitting states decreases; Small intrastrand hopping integral does not seem to diminish the transmission coefficient, but shrinks the location in the three-dimension figure. And the distribution of energy is concentrated.

Abstract: We focused on the inability of the common high-low method to detect very fast interface states, and developed methods to evaluate such states (Cψ_S method). We have investigated correlation between the interface state density (D_IT) evaluated by the Cψ_S method and MOSFET performance, and found that the D_IT(Cψ_S) was well reflected in MOSFET performance. Very fast interface states which are generated by nitridation restricted the improvement of subthreshold slope and field-effect mobility.

Abstract: Carboxyl-modified graphene materials in both oxide and reduced state were explored in parallel for the preparation of field-effect transistors (FET). They were solution gated by phosphate buffer solution (PBS) (pH 7.2). Their conductance were examined and compared with unmodified graphene transistors, firstly. Then, after single strand DNA molecules were immobilized on reduced and oxide graphene transistors, their conductance and compared. Here ssDNA molecules were amino-tagged at the terminal five. It was found that ambipolar characteristic was exhibited by reduced graphene transistors, even they were undergone carboxyl modification. And it was also discovered that there were opposite conductance variation with the increasing of ssDNA concentrations and bigger changes were obtained by reduced carboxyl-modified graphene transistors.

Abstract: The accurate electrical properties of semiconductor GaN based blue Light-Emitting Diodes (LED) with Multiple-Quantum Well (MQW) structure and GaAsP based red LED, were measured by single Capacitance-Voltage (C-V) method and single Current-Voltage (I-V) method at large forward bias. After comparing the experimental results, we found that the apparent capacitance C_p of GaN based blue LED and GaAsP based red LED measured by C-V method display obviously negative value at large forward bias and low frequency, which is in conflict with the well known Shockley's p-n junction theory and model. Besides, the precise Characterization of apparent capacitance C_p and apparent conductance G_p is obtained.