Surface Leakage Research Articles

Etching of m-plane Zn(Mg)O epitaxial films and its impact on surface leakage currents

Zinc oxide is a novel material system for mid-infrared and THz optoelectronics. Especially its non-polar m-plane orientation is a promising candidate for the design of devices like quantum cascade lasers (QCLs) and detectors (QCDs). But for their realization novel fabrication schemes are needed. We present a new inductively coupled plasma reactive ion etching (ICP-RIE) process for etching of m-Zn(Mg)O heterostructures in a CH4-based chemistry. The process has been optimized for smooth vertical sidewalls together with high selectivity towards a SiN etch mask. This was achieved by combining the RIE etching with wet chemical etching in strongly diluted HCl. Similar to various types of semiconductor-based optoelectronic materials and devices (Sidor et al 2016 J. Electron. Mater. 45 4663–7; Ma et al 2016 Opt. Express 24 7823), including other wide-gap semiconductors like (In)GaN (Zhang et al 2015 Nanotechnology 26), we observe surface leakage currents in etched m-plane Zn(Mg)O structures. We show that they depend on the applied etching process and surface treatment techniques as well as the barrier composition in the Zn(Mg)O heterostructures. In addition, a treatment in hydrogen peroxide (H2O2) yields a significant surface leakage current suppression up to several orders of magnitude.

Reduced Reverse Gate Leakage Current for p‐GaN Gate High‐Electron‐Mobility Transistors by a Surface‐Etching Method

Herein, the mechanism of increased gate leakage current observed in SiNx‐passivated high‐resistivity cap layer high‐electron‐mobility transistors (HRCL‐HEMTs) is investigated. The leakage is found to be correlated with the roughened morphology and deviated surface stoichiometry caused by H‐plasma treatment. An additional step of surface etching before passivation restores GaN surface and gate leakage is reduced by about two orders of magnitude, whereas the other electrical characteristics of p‐GaN HEMTs are preserved.

Temperature effects on gated silicon field emission array performance

Silicon field emitter arrays (Si FEAs) are being explored as an electron source for vacuum channel transistors for high temperature electronics. Arrays of 1000 × 1000 silicon tip based gated field emitters were studied by measuring their electrical characteristics up to 40 V of DC gate bias with a 1.3 mA emission current at different temperatures from 25 to 400 °C. At ∼350 °C, residual gas analyzer measurements show that water desorption and carbon dioxide partial pressures increase significantly, the gate to emitter leakage current decreases by more than ten times, and the collector current increases by more than ten times. These improvements remained after heat-treatment but were then lost once the device was exposed to the atmosphere for several days. The improvements could be recovered upon additional baking suggesting that adsorbates (primarily water) on the surface affected field emission and surface leakage. It was also found that after heat-treatment, the electrical characteristics of the devices exhibited <3% variation in collector current at 40 V, which (without exposure to the atmosphere) can be termed as a weak temperature dependence. These results suggest that Si FEAs could be viable as a high temperature transistor.

Effect of Biased Neighboring Wire on Polysilicon Wire Biosensors with Sensing Membrane of γ-APTES Mixed with Polydimethylsiloxane-Treated Silica Nanoparticles

Voltages simultaneously applied to two adjacent nanoscale sensors in sensor array might cause false readings. In this work, we investigated the interference effect resultant from a biased neighboring wire on the pH sensing characteristics of the polysilicon wire (PSW) sensors array with sensing membranes of 3-aminopropyltrimethylsiloxane (γ-APTES) and polydimethylsiloxane (PDMS)-treated silica nanoparticles (NPs) plus UV light exposure (γ-APTES + NPs + UV). The current-voltage (I–V) characteristics of the PSW sensors were used to measure the buffer solutions with different pH values under the influences of a neighboring PSW biased with a constant voltage. It is found that, under the influence of the biased neighboring PSW, the sensing channel currents of the PSW with γ-APTES sensing film are much lower than those of the PSW sensor with γ-APTES + NPs + UV sensing film, while the channel current deviation errors of the PSW with γ-APTES sensing film are much higher than those with γ-APTES + NPs + UV sensing film. These improvements are ascribed to the smaller surface leakage current and superior molecular structure of the γ-APTES + NPs + UV sensing film. Apparently, the γ-APTES + NPs + UV sensing film is a better choice for PSW array sensors.

Effects of Al Composition and High-Temperature Atomic Layer-Deposited Al2O3 Layer on the Leakage Current Characteristics of AlGaN/GaN Schottky Barrier Diodes

AlGaN/GaN Schottky barrier diodes (SBDs) with high Al composition and high temperature atomic layer deposition (ALD) Al2O3 layers were investigated. Current–voltage (I–V), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and capacitance–voltage (C–V) measurements were conducted in order to find the leakage current mechanism and reduce the reverse leakage current. The fabricated AlGaN/GaN SBDs with high Al composition exhibited two orders’ higher leakage current compared to the device with low Al composition (20%) due to large bulk and surface leakage components. The leakage current measured at −60 V for the fabricated SBD with Al2O3 deposited at temperature of 550 °C was decreased to 1.5 μA, compared to the corresponding value of 3.2 mA for SBD with nonpassivation layer. The high quality ALD Al2O3 deposited at high temperature with low interface trap density reduces the donorlike surface states, which effectively decreases surface leakage current of the AlGaN/GaN SBD.

Темновые токи униполярных барьерных структур на основе теллурида кадмия и ртути для длинноволновых инфракрасных детекторов

Two types of long-wave infrared nBn structures based on mercury cadmium telluride grown by molecular beam epitaxy on GaAs (013) substrates have been fabricated. For each type of device, the side walls of the mesa structures were passivated with an Al2O3 dielectric film or left without passivation. The CdTe content in the absorbing layers was 0.20 and 0.21, and in the barrier layers, 0.61 and 0.63. The dark currents of the manufactured devices were studied in a wide range of voltages and temperatures. The values of the surface leakage component are found under various conditions. It has been shown that the surface leakage current density decreases upon passivation with an Al2O3 film. It was found that at room temperature in the fabricated nBn structures with reverse biases, the surface leakage component dominates, and with forward biases, the dark current is determined by the combined effect of the surface leakage component and the bulk current component. From the Arrhenius plots, the values of the activation energies of the surface leakage current component were found, which at small reverse biases are in the range from 0.05 to 0.10 eV. At small reverse biases, upon cooling the samples, the role of the bulk component of the dark current increases, which at 180 K is approximately 0.81 A/cm2. In the temperature range 200-300 K, the values of the dark current density exceed the values calculated according to the empirical Rule07 model by a factor of 10-100, which indicates the possibility of creating long-wave infrared barrier detectors with a decrease in the values of the surface leakage component.

Negative Schoch displacement of two-dimensional acoustic metamaterials with near-zero refractive index

In this paper, the Schoch displacement at the interface between different two-dimensional triangular phononic crystal metamaterial and natural material is studied by using finite element software. As is well known, the Schoch displacement is highly dependent on the surface wave and leakage wave excited at the interface between different materials. So, the negative Schoch displacement can be more easily obtained by adding a suitable thickness of covering layer at the interface between metamaterial material and natural material. The numerical results show that when the negative Schoch displacement happens, the effective parameters of metamaterials are close to zero. It means that the effective refraction index is near to zero and the reduced frequency of the incident acoustic wave is correlated with the reduced frequency of the band gap. It is also found from the results that the reduced frequency of the incident acoustic wave is located at the edge of the band gap when the negative Schoch displacement occurs. The maximum of the metamaterial effective impedance and the maximum of the reflection coefficient are almost at the same frequency. The phase of the imaginary part of the reflection coefficient has a phase mutation in π rad at the corresponding frequency. The frequency of negative Schoch displacement is located in the first band gap of <i>MK</i> direction and near the upper boundary. The Schoch displacement at the interface between conventional materials is usually positive and negligible in previous reports. In this paper, the negative Schoch displacement is obtained by using the near-zero refraction index metamaterials. This not only enriches the physics contents of Schoch effect but also provides a theoretical reference for designing the acoustic devices based on acoustic wave displacement at the interface.

High Hole Mobility and Low Leakage Thin-Body (In)GaSb p-MOSFETs Grown on High-Bandgap AlGaSb

In this study, we demonstrated low leakage current and high mobility thin body (In)GaSb p-FETs. Through the optimization of the V/III ratio during the epitaxial growth, we achieved a highly insulating bottom Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.95</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.0</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> Sb barrier, which eliminates the junction leakage. We also suppressed the interface trap-assisted surface leakage current by introducing In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</sub> As surface passivation on the GaSb channel. Furthermore, GaSb/InGaSb/GaSb quantum well (QW) channel structure provided significant improvement in effective mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu }_{\mathrm{ eff}}$ </tex-math></inline-formula> ) characteristics. As a result, the fabricated devices showed the lowest off-leakage current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I} _{\mathrm{ off}}$ </tex-math></inline-formula> ), subthreshold slope ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> . <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> .) and high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\mathrm{ eff}}$ </tex-math></inline-formula> among reported GaSb p-MOSFETs.

Effects of glycerol and sodium pentaborate containing new formulation on sleeve gastrectomy model in rats.

ABSTRACTPurpose:The development of cutting surface leakage and postoperative peritoneal adhesions (PPA) after sleeve gastrectomy (SG) are the most serious operative complications. We investigated the effectiveness of the newly developed glycerol and sodium pentaborate containing formulation on the prevention of these complications.Methods:Sixteen Sprague Dawley rats (mean weight 310 ± 50 g, mean age 3 months old) were divided into two groups, consisting of eight rats in each. SG and a double-layer suture technique were performed for each group. In study group, there was the mixture of 2 mL 3% glycerol plus 3% sodium pentaborate formulation, and in the control group 2 mL 0.9% NaCl was injected into the peritoneal cavity. Rats were sacrificed after 30 days, then macroscopic adhesion grade scoring and histopathological evaluations were assessed.Results:Macroscopic PPA scores in the control and study groups were 2.75 ± 0.16 and 1.50 ± 0.327, respectively (p = 0.004). Histopatologic fibrosis scores in the control and study groups were 0.87 ± 0.125 and 2.00 ± 0.26, respectively (p = 0.002).Conclusions:In SG operation model, glycerol plus sodium pentaborate compound decreased PPA formation and also increased stomach cut surface line fibrosis. This new formulation is hopeful for more safe SG operations.

Interface Optimization and Modulation of Leakage Current Conduction Mechanism of Yb2O3/GaSb MOS Capacitors With (NH4)2S Solutions Passivation

In current work, the impact of ammonium sulfide (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S solution passivation with varied pH value on the Yb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /n-GaSb interface has been investigated comparatively. Compared with control samples, the neutral (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S solution passivation can effectively reduce oxides layer on GaSb surface and gate leakage via X-ray photoelectron spectroscopy(XPS) measurements and electrical characterization. High-low frequency capacitance method was used to evaluate interface-state density Dit, it was found that capping with Yb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> can delaythe interface-state generation and the lowest Dit value of 5.18 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> eV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for Yb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /GaSb capacitor with neutral (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S was achieved. Moreover, the possible leakage current conduction mechanisms for capacitors measured at room temperature and low temperature have also been discussed systematically.

Surface leakage current reduction of InAsSb nBn MWIR HOT detector via hydrogen peroxide treatment

InAsSb nBn structure plays a key role in realizing high operating temperature (HOT) MWIR detectors. However, the AlAsSb layer, functioning as a barrier layer, can be rapidly oxidized during the pixel isolation process, forming undesirable oxides that can contribute to increase the surface leakage current. In this work, electrical and optical analysis were performed to investigate the role of the post-treatment process after pixel isolation step in reducing the oxidation and inhibiting the formation of unfavorable oxides closely related to the surface leakage currents. Our study shows that H2O2 post-treatment after the dry pixel isolation process can effectively reduce the barrier oxidation and suppress the formation of Sb2O5, greatly reducing the surface leakage current. Using the proposed post-treatment process, the dark current density of less than 1 × 10−6 A/cm2 was obtained at an applied bias of −0.3 V and 150 K, which is one order of magnitude lower than that of the InAsSb nBn device recently reported.

Leakage current signal parameter of various surface roughness conditions of field-aged polymer insulators

This paper presents the signal parameter of leakage current based on various surface roughness degradation conditions for field-aged high voltage polymer insulators. The arithmetical mean of surface roughness is measured accordingly, and also the surface leakage current signal is captured effectively using data acquisition device via the electrical stress test. With the variation of field-aged insulators ages which include 6-year, 12-year and 18-year, they have been mechanically tested using a surface roughness tester along with electrical testing by using the standard method of inclined plane test. The surface roughness data are recorded meanwhile the leakage current signals are further analyzed using Spectrogram to extract the signal parameter. These include the instantaneous root mean squared current, the instantaneous total harmonic distortion, the instantaneous total non- harmonic distortion and the instantaneous total waveform distortion. From the results of the comparative study, it has shown that the statistical quantity of leakage current signal parameters is responding in an increasing trend with respect to the incremental of the surface roughness. Thus, the signal parameters of the leakage current are able to indicate the degradation conditions of insulator surface.

Hydro-biogeochemical processes of surface water leakage into groundwater in large scale karst water system: A case study at Jinci, northern China

Surface water leakage and anthropogenic inputs into groundwater prevail in karst areas in China. In this paper, surface and ground water were collected and multiple isotopic tracers were integrated with hydrogeochemical parameters to characterize the residence time, recharge history, biogeochemical processes, surface leakage and anthropogenic influences in Jinci karst system. Most karst groundwater have depleted δ18O and δ2H values together with 14C ages of 3000–11,085 years. Several karst groundwater along the Fenhe River channel show remarkable enrichment of oxygen and hydrogen and young apparent 14C ages (60–1845 years), signifying recently communicating with surficial environment. Major anthropogenic components in the surface water (Na+, Cl− and NO3−) and nutrients leak into groundwater along Fenhe River. Additionally, surface water leakage changes the microbial community in phylum and family levels for groundwater. The calculated river water leakage flux for the possible affected groundwater range from 61% to 87%, with the highest serious leakage found in Hekou county. Dominated by Ca2+, Mg2+, HCO3− and SO42−, the hydrogeochemical evolution of surface and ground water in the study area are largely controlled by dissolution of calcite, dolomite with gypsum and dedolomitization. Discharge of coal mine drainages and unregulated disposal of domestic sewage also contribute substantially to the groundwater hydrogeochemistry along the river leakage section, confirmed by lower δ34S values (1.8‰–4.7‰), depleted δ13C compositions (−12.2‰ to −10.4‰) and enriched δ18O and δ2H values. Karst groundwater in Hekou county show the highest contribution of coal mine drainage (36.4%) and moderate contribution of domestic sewage (8.6%).

Investigation of the electrical conduction mechanisms in P-type amorphous germanium electrical contacts for germanium detectors in searching for rare-event physics

For the first time, electrical conduction mechanisms in the disordered material system is experimentally studied for p-type amorphous germanium (a-Ge) used for high-purity Ge detector contacts. The localization length and the hopping parameters in a-Ge are determined using the surface leakage current measured from three high-purity planar Ge detectors. The temperature dependent hopping distance and hopping energy are obtained for a-Ge fabricated as the electrical contact materials for high-purity Ge planar detectors. As a result, we find that the hopping energy in a-Ge increases as temperature increases while the hopping distance in a-Ge decreases as temperature increases. The localization length of a-Ge is on the order of 2.13^{-0.05}_{+0.07}mathrm{{A}}^circ to 5.07^{-0.83}_{+2.58}mathrm{{A}}^circ , depending on the density of states near the Fermi energy level within bandgap. Using these parameters, we predict that the surface leakage current from a Ge detector with a-Ge contacts can be much smaller than one yocto amp (yA) at helium temperature, suitable for rare-event physics searches.

Impedance of MIS Devices Based on nBn Structures from Mercury Cadmium Telluride

Three types of nBn structures based on mercury cadmium telluride grown by molecular beam epitaxy have been fabricated. As barrier layers in nBn structures, Hg1–xCdxTe at x = 0.67 and 0.84 and the 18 period Hg0.20Cd0.80Te (9 nm) – HgTe (2 nm) superlattice were used. To study the properties of barrier layers based on nBn structures, MIS devices were created using dielectric Al2O3 films. The impedance of the created devices was investigated over wide ranges of voltages, frequencies, and temperatures. Equivalent circuits of MIS devices based on nBn structures in the accumulation mode are proposed. It is shown that measurements of the frequency dependences of the impedance make it possible to determine the values of the differential resistance of the barrier layer in a wide range of conditions. It was found that the values of the differential resistance are determined only by the bulk component of the dark current, and the surface leakage component does not affect the measured impedance of MIS devices. The dependences of the values of the equivalent circuit elements on the area of structures, voltage, and temperature are determined. It is shown that in the temperature range 210–300 K, the values of the differential resistance of the barrier layer based on Hg0.33Cd0.67Te are determined by the diffusion-limited flow of holes from the contact and absorbing layers, at the forward and reverse biases, respectively. The values of the product of the differential resistance and the area are determined for nBn structures with various parameters of the barrier layers. The possibilities of using the measurements of impedance of MIS devices based on nBn structures to study the homogeneity of properties of various layers are demonstrated..

Prediction of surface leakage current of overhead insulators under environmental and electrical stresses

Leakage current is one of the critical aspects to consider for overhead transmission line insulator’s condition and performance assessment. As the leakage current increase, the size of the dry band also will increase leads to the dry band arcing, deteriorate the insulator performance and contribute to the development of insulator flashover. Based on the literature study, other than the existence of contaminations on the surface of insulator combined with moisture, the variation in leakage current is also affected by the environmental and electrical stresses. Previous researches have shown the effect of environmental and electrical stresses on surface leakage current based on experimental and simulation results. This paper outlines an analytical approach based on dimensional analysis to propose a new mathematical model of leakage current under environmental and electrical stresses. To justify the applicability of the derived dimensional model, the new model has been validated using previous researcher’s experimental results. The validation indicated that the proposed model had shown a good agreement with the previous experimental results. The proposed dimensional equation for this research work can be potentially used as a predictive performance model to evaluate and monitor the leakage current and insulator’s performance

Suppression of Surface Leakage Currents in InAs Avalanche Photodiodes via Sputtering of High-k Dielectric Layers

The effectiveness of a range of alternative high- ${k}$ dielectric layers as potential passivation layers for InAs avalanche photodiodes has been investigated. The suppression of surface leakage currents is investigated by analyzing the current–voltage performance of differently sized mesa diodes passivated with each oxide layer. Three potential passivation layers, such as ZnO, Al2O3, and MgO, have been identified, all of which enables the suppression of surface leakage in smaller sized devices of a radius of $50~\mu \text{m}$ and at lower temperatures of 175 K compared to a reference SU8 device. The influence of repeated temperature cycling on these layers has also been investigated with Al2O3 passivated devices, exhibiting no change in performance after multiple cooling and heating cycles.

High speed and ultra-low dark current Ge vertical p-i-n photodetectors on an oxygen-annealed Ge-on-insulator platform with GeOx surface passivation.

Germanium (Ge) vertical p-i-n photodetectors were demonstrated with an ultra-low dark current of 0.57 mA/cm2 at -1 V. A germanium-on-insulator (GOI) platform with a 200-mm wafer scale was realized for photodetector fabrication via direct wafer bonding and layer transfer techniques, followed by oxygen annealing in finance. A thin germanium-oxide (GeOx) layer was formed on the sidewall of photodetectors by ozone oxidation to suppress surface leakage current. The responsivity of the vertical p-i-n annealed GOI photodetectors was revealed to be 0.42 and 0.28 A/W at 1,500 and 1,550 nm at -1 V, respectively. The photodetector characteristics are investigated in comparison with photodetectors with SiO2 surface passivation. The surface leakage current is reduced by a factor of 10 for photodetectors via ozone oxidation. The 3dB bandwidth of 1.72 GHz at -1 V for GeOx surface-passivated photodetectors is enhanced by approximately 2 times compared to the one for SiO2 surface-passivated photodetectors. The 3dB bandwidth is theoretically expected to further enhance to ∼70 GHz with a 5 µm mesa diameter.

Effect of fluorinated graphene insulator on AlGaN/GaN MIS-HEMTs as gate dielectric

We investigate the performance of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) by inserting a fluorinated graphene insulator. It is found that the interface-state density of the sample with fluorinated graphene (5.8 × 1013–8.7 × 1011 eV−1·cm−2) was lower than that without fluorinated graphene (1.1 × 1014–8.1 × 1012 eV−1·cm−2) and exhibits better properties, including higher saturation drain current (Isat), lower on-resistance (Ron), smaller hysteresis of threshold voltage (ΔVth), and better current collapse suppression. Furthermore, the inserted fluorinated graphene could increase the activation energy of surface leakage current, which is verified by the analysis of leakage current. Our results suggest that the fluorinated graphene insulator can lessen interface-state density at the shallow energy levels by the interface-state density decrement and the activation energy increment.

A comparison study regarding Al/p-Si and Al/(carbon nanofiber–PVP)/p-Si diodes: current/impedance–voltage (I/Z–V) characteristics

Al/p-Si and Al/(carbon nanofiber–PVP)/p-Si diodes were produced using a p-type silicon wafer with 10 Ω cm resistivity to determine the polymer interlayer effects on device characteristics. To assess whether carbon nanofiber–PVP interlayer is beneficial for electrical performance, the current–voltage (I–V) and the impedance–voltage (Z–V) measurements were performed in wide range of voltage. Thus, electrical parameters such as series resistance, barrier height, and ideality factor were derived from the forward bias Ln (IF)–VF and Cheung’s functions, so that they are compared and voltage dependence of them is explored. Later, the values of intercept voltage, width of depletion layer, doping acceptor atom concentration, and barrier height were also extracted from C−2–V data at 1 MHz and then results were compared with each other. The surface states and their energy profile were also extracted from the IF–VF characteristics by considering barrier height (BH) and n is voltage dependent as well. Experimental results indicate that the carbon nanofiber–PVP interlayer decreases surface states (Nss), series resistance (Rs) and leakage current, whereas it increases rectifying ratio and shunt resistance. Hence, such polymeric interlayer material forms an interesting alternative to conventional oxide layer due to some advantages of polymers such as desirably low values of cost, weight, and energy consumption.