- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
The characteristics of Cu(In, Ga)Se2 thin-film solar cells by bandgap grading
摘要： The performance of CIGSe-1 and CIGSe-2 absorber layers are compared with Eg grading such that a higher Ga content is incorporated into the back region. A wider depth range of the high-Ga region near the back of a CIGSe absorber layer can reduce its performance due to the increased formation of Ga-related defects and defect clusters. Therefore, for an Eg-graded CIGSe layer with a wider Eg on the back surface, appropriate Eg grading can improve its performance.
关键词： CIGSe,bandgap grading,defect,surface potential,solar cell
更新于2025-11-14 17:28:48
-
Carrier behavior in the vicinity of pit defects in GaN characterized by ultraviolet light-assisted Kelvin probe force microscopy
摘要： Surface potentials in the vicinity of V-pits (cone bottom) and U-pits (blunt bottom) on epitaxial GaN surface have been systematically studied using ultraviolet (UV) light-assisted Kelvin probe force microscopy (KPFM). The band structure models are established to understand variation of the surface potentials at the pits and planar surface with and without UV light. The photo-generated carrier behavior at the pit defects is studied. According to the surface potential results, it can be deduced that the carrier distributions around the V- and U-pits are uneven. In dark, the electron concentration at the bottom of V-pit (30n0) and U-pit (15n0) are higher than that at planar surface (n0). Under UV light, for V-pit, the electron concentration at the cone bottom (4.93×1011n0) is lower than that at the surrounding planar surface (5.68×1013n0). For U-pit, the electron concentration at the blunt bottom is 1.35×1012n0, which is lower than that at the surrounding planar surface (6.13×1013n0). The non-equilibrium electron concentrations at different locations are calculated. Based on the non-equilibrium electron concentration, it can be concluded that the carrier recombination rate at pit defects is higher than that at planar surface.
关键词： pit defects,electron concentration,surface potential
更新于2025-09-23 15:23:52
-
Measurement of Forces between Supported Cationic Bilayers by Colloid Probe Atomic Force Microscopy: Electrolyte Concentration and Composition
摘要： The interactions between supported cationic surfactant bilayers were measured by colloidal probe atomic force spectroscopy, and the effect of different halide salts was investigated. Di(alkylisopropylester)dimethylammonium methylsulfate (DIPEDMAMS) bilayers were fabricated by the vesicle fusion technique on muscovite mica. The interactions between the bilayers were measured in increasing concentrations of NaCl, NaBr, NaI, and CaCl2. In NaCl, the bilayer interactions were repulsive at all concentrations investigated, and the Debye length and surface potential were observed to decrease with increasing concentration. The interactions were found to follow the electrical double layer (EDL) component of DLVO theory well. However, van der Waals forces were not detected; instead, a strong hydration repulsion was observed at short separations. CaCl2 had a similar effect on the interactions as NaCl. NaBr and NaI were observed to be more efficient at decreasing surface potential than the chloride salts, with the efficacy increasing with the ionic radius.
关键词： supported bilayers,DLVO theory,Debye length,surface potential,halide salts,colloidal probe atomic force spectroscopy
更新于2025-09-23 15:23:52
-
Metal nanowire–polymer matrix hybrid layer for triboelectric nanogenerator
摘要： In this work, we studied the surface potential of a metal–polymer hybrid layer and its effect on the performance of a triboelectric nanogenerator (TENG). Ag nanowires (AgNWs) separately embedded in two different polymers–one with a positive tribopotential and the other with a negative tribopotential–were prepared as model hybrid systems. The surface potentials of the hybrid system were systematically investigated by Kelvin probe force microscopy. The results demonstrated that each component of the hybrid layer affected the other component because of the difference in their work functions. The following two important findings were obtained. First, the surface potential of each polymer shifted drastically toward that of Ag and the surface potential of Ag shifted toward that of each polymer. Second, higher density of AgNWs led to higher Ag-induced charge density in the polymer, which consequently resulted in larger shift in the surface potential of the polymer. TENG performance measurements revealed that the tribopotential difference between the contact surfaces of the AgNW–polymer hybrid layer and the perfluoroalkoxy alkane (or Nylon) used as the top triboelectric layer governed the TENG performance. Our systematic investigation of the surface potential of a hybrid surface consisting of two materials with different surface potentials provides insight into the design of triboelectric layers for high-performance TENGs.
关键词： triboelectric nanogenerator,silver nanowire,kelvin probe force microscopy,hybrid,surface potential
更新于2025-09-23 15:22:29
-
A Surface Potential Based Model for Dual Gate Bilayer Graphene Field Effect Transistor Including the Capacitive Effects
摘要： In this work, a surface potential modeling approach has been proposed to model dual gate, bilayer graphene field effect transistor. The equivalent capacitive network of GFET has been improved considering the quantum capacitance effect for each layer and inter-layer capacitances. Surface potentials of both layers are determined analytically from equivalent capacitive network. The explicit expression of drain to source current is established from drift-diffusion transport mechanism using the surface potentials of the layers. The drain current characteristics and transfer characteristics of the developed model shows good agreement with the experimental results in literatures. The small signal parameters of intrinsic graphene transistor i.e. output conductance (gds), trans-conductance (gm), gate to drain capacitance (Cgd) and gate to source capacitance (Cgs) have been derived and finally, the cut-off frequency is determined for the developed model. The model is compared with reported experimental data using Normalised Root Mean Square Error (NRMSE) metric and it shows less than 16% NRMSE. A Verilog-A code has been developed for this model and a single ended frequency doubler has been designed in Cadence design environment using this Verilog-A model.
关键词： model,Field-effect transistor (FET),Verilog-A,Graphene,surface potential,frequency doubler.
更新于2025-09-23 15:22:29
-
Numerical model for the chemical adsorption of oxygen and reducing gas molecules in presence of humidity on the surface of semiconductor metal oxide for gas sensors applications
摘要： Charge transfer between the interacting gas molecules and the surface of the sensing layer is the main mechanism for the detection of gases in semiconductor metal oxides. In the presented work, the Wolkenstein's theory of adsorption is used instead of the conventional Langmuir isotherm for the numerical modelling of adsorption of oxygen, reducing gas (CO) molecules and water vapours. A numerical model of chemical adsorption of these gas species at the surface of tin oxide (SnO2) semiconductor gas sensor is presented in this paper. Using this model, quantitative calculation of the combined effect of environmental oxygen, reducing gas (CO) and water vapor adsorption on various electronic properties like electrical conductivity, surface potential and the work function of the metal oxide surface has been carried out. The surface coverage of the chemically adsorbed oxygen gas molecules is simulated as a function of oxygen gas pressure, the temperature of the sensor surface and bulk doping level of the n-type SnO2 semiconductor. Along with oxygen, the adsorption of CO gas is simulated as a function of CO gas pressure at constant atmospheric pressure of Oxygen gas. Furthermore, the sensor response is simulated and compared both in presence of dry Carbon Monoxide (CO) gas as well in the humid environment. It is shown that in the presence of water vapor there is an increase in the conductivity due to the decrease in the surface potential barrier at the semiconductor surface.
关键词： Numerical model,Surface potential,Chemical adsorption,Gas sensor
更新于2025-09-23 15:21:01
-
The analysis of the electrical characteristics and interface state densities of Re/n-type Si Schottky barrier diodes at room temperature
摘要： The main electrical characteristics of current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature of the Re/n-type Si Schottky barrier diodes prepared by pulsed laser deposition (PLD) method have been examined. The values of the basic electrical properties such as forward saturation current (Io), ideality factors (n), barrier heights (Фbo), recti?cation ratio (RR) and series resistances (RS) were obtained from I-V and C-V measurements using di?erent calculation methods. At low voltages (V ≤ 0.3 V), the electrical conduction was formed to take place by thermionic emission, whereas at high voltages (V > 0.3 V), a space charge limited conduction mechanism was shown. Furthermore, the interface state densities (NSS) as a function of energy distribution (ESS- EV) was obtained from the I-V data by taking into account the bias dependence of the e?ective barrier height (Φb) for the Re/n-type Si Schottky barrier diodes.
关键词： interface states,surface potential,recti?cation ratio,Electrical parameters,series resistance
更新于2025-09-23 15:21:01
-
Nanoscale charge transport and local surface potential distribution to probe defect passivation in Ag doped Cu2ZnSnS4 absorbing layer
摘要： The performance of earth abundant Cu2ZnSnS4 (CZTS) material is limited by high deficit of open circuit voltage (VOC) which is mainly due to the easy formation of CuZn antisite defects. Suppression of CuZn defects is thus inevitably required for further developments in CZTS based solar cells. We studied systematic increase of Ag doping in CZTS thin film and investigated the nanoscale electrical properties using kelvin probe force microscopy (KPFM) and current sensing atomic force microscopy (CAFM) to probe CuZn defects. Crystallographic analysis indicated the successful partial substitution of Cu+ ions by large size Ag+ ions. The considerable decrease in grain boundary potential from 66.50 ± 5.44 mV to 13.50 ± 2.61 mV with Ag doping, suggesting the substantial decrease in CuZn defects. Consequently, CAFM measurement confirms the remarkable increment in minority carrier current with Ag doping and their local mobility in CZTS layer. Finally, the lower persistent photoconductivity (PPC) and fast decay response of photogenerated carriers for Ag doped CZTS photodetector further validate our results. This study provides a fresh approach of controlling deleterious CuZn defects in CZTS by tuning Ag content that may guide researchers to develop next generation high performance CZTS based solar cells.
关键词： nanoscale surface potential and current,CZTS solar cells,Ag doped CZTS,defects,photodetector
更新于2025-09-23 15:21:01
-
[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Single-Crystalline Metal Oxide, Resistive Gas Sensors Advances and Perspectives
摘要： Here we review recent results on the synthesis of single-crystalline metal oxide nanomaterials and their integration in resistive gas sensing devices. Emphasis is put on the integration of such nanomaterials in a wide spectrum of transducing platforms, ranging from standard ceramic to silicon MEMS or flexible polymeric. Some strategies for achieving higher selectivity are discussed, which are followed by a discussion on the development of advanced operation techniques for achieving more stable and faster response to gases. Finally, some aspects that remain open for research are identified.
关键词： surface potential control,nanowires,nanoparticles,chemoresistors,metal oxides,UV light excitation
更新于2025-09-19 17:15:36
-
Controlled synthesis of colloidal monodisperse gold nanoparticles in a wide range of sizes; investigating the effect of reducing agent
摘要： The diverse applications of gold nanoparticles (Au-NPs) with sizes less than 50nm require a comprehensive information about how to produce Au-NPs with different sizes and narrow size distributions for a desired application. In this work, a wide range of sizes of Au-NPs from 2.5 to 35nm has been synthesized by using two reducing agents of sodium citrate and sodium borohydride. We have studied the dependency of the size, polydispersity, surface potential, plasmonic spectrum, and pH of the resultant Au-NPs on the reducing agents' concentrations. The findings show that uniform and monodispersed Au-NPs can only be produced in specific ranges of concentrations of the reducing agents. In addition, the absorption spectra of Au-NPs cannot uniquely determine the dominant size of the nanoparticles and polydispersity of the sizes is an important parameter. Measuring Zeta potential of the Au-NPs shows that by increment of pH of the solutions, the surface potential in both methods monotonically increases which results in more stability of the nanoparticles.
关键词： Polydispersity,Gold Nanoparticles,Size Distribution,Reducing agent,Surface Potential
更新于2025-09-19 17:13:59