Temperature Dependence Of Barrier Height Research Articles

Investigations on interface charge conduction mechanisms for chemically grown manganite – Manganite structure: Hysteretic current – Voltage characteristics

In the present study, high quality LaMnO3–δ/La0·7Ca0·3MnO3/LaAlO3 (LMO/LCMO/LAO) manganite – manganite structure was successfully prepared using low cost chemical solution deposition (CSD) method. Temperature dependent resistive switching (RS) was performed across the manganite – manganite structure and various electronic processes have been employed to understand observed RS behavior. Various theoretical models have been used to understand the charge conduction involved in the hysteretic current – voltage (I–V) characteristics at different temperatures. Charge carrier conduction processes have been investigated for separate I–V cycles of RS characteristics where thermionic emission and space charge limited conduction mechanisms have been identified as appropriate charge carrier conduction mechanisms. Temperature dependent barrier height and other obtained fitting parameters have been discussed in detail.

Electrical evolution of W and WC Schottky contacts on 4H-SiC at different annealing temperatures

In this paper, we investigate the electrical evolution of tungsten (W) and tungsten carbide (WC) Schottky contacts on 4H-SiC subjected to thermal treatments at different annealing temperatures from 475 °C to 700 °C. For each annealing temperature, the uniformity of the Schottky barrier height (ΦB) and ideality factor (n) was monitored by current–voltage (I–V) measurements in forward bias, performed over sets of equivalent diodes. Good values of n (below 1.05) were found for both contacts up to thermal annealing at 700 °C. On the other hand, the barrier of the two contacts behaves differently. For the W/4H-SiC diode, the ΦB increases with the annealing temperature (from 1.14 eV at 475 °C to 1.25 eV at 700 °C), whereas the Schottky barrier in WC/4H-SiC features a slight reduction already with thermal annealing at 475 °C, remaining almost constant at around 1.06 eV up to annealing at 700 °C. A deeper characterization was performed on the 700 °C-annealed contacts by studying the temperature-dependence of the Schottky parameters by current–voltage–temperature (I–V–T) characterization. The ΦB and n behaviour with temperature indicates the presence of a nanoscale lateral inhomogeneity for both Schottky contacts, which can be described by Tung’s model. Finally, the temperature-dependence of the reverse characteristics could be described by the thermionic field emission model, accounting for the temperature dependent barrier height determined from forward characterization.

Annealing effect on I-V and C-V characteristics of Al/n-InP Schottky diodes at low temperatures

In this study, Schottky contacts have been fabricated on n-InP (100) using an Al/n-InP/In configuration. The current voltage (I-V) and capacitance voltage (C-V) characteristics of Al/n-InP/In Schottky diodes were calculated from the liquid nitrogen temperature to the room temperature by steps of 10 K before annealing of this structure and after annealing at 400 °C for 3 min. The series resistance, ideality factor and barrier height values calculated using I-V characteristics, Cheung functions, Norde (F-V) functions, and C-V characteristics before and after annealing the contact and compared for each temperature. These measurements clearly showed that the Al/n-InP/In Schottky diode became extremely stable due to the annealing process and the mean barrier height value have been increased from 0,494 to 0,674 eV after thermal annealing at 400 °C. In addition, temperature dependent barrier height values of as-fab. and annealed (at 400 °C) Al/n-InP/InSchottky contacts are consistent with “the barrier inhomogeneous model” of Schottky diodes.

Electrical properties of inhomogeneous tungsten carbide Schottky barrier on 4H-SiC

In this paper, the electrical behavior of tungsten carbide (WC) Schottky barrier on 4H-SiC was investigated. First, a statistical current-voltage (I–V) analysis in forward bias, performed on a set of equivalent diodes, showed a symmetric Gaussian-like distribution of the barrier heights after annealing at 700 °C, where a low Schottky barrier height (ΦB = 1.05 eV) and an ideality factor n = 1.06 were measured. The low value of the barrier height makes such a WC contact an interesting candidate to reduce the conduction losses in 4H-SiC Schottky diodes. A deeper characterization has been carried out, by monitoring the temperature dependence of the I–V characteristics and the behavior of the relevant parameters ΦB and n. The increase of the barrier height and decrease of the ideality factor with increasing temperature indicated a lateral inhomogeneity of the WC/4H-SiC Schottky contact, which was described by invoking Tung’s model. Interestingly, the temperature dependence of the leakage current under reverse bias could be described by considering in the thermionic field emission model the temperature dependent barrier height related to the inhomogeneity. These results can be useful to predict the behavior of WC/4H-SiC Schottky diodes under operative conditions.

Temperature-dependent barrier height inhomogeneities in PTB7:PC71BM-based organic solar cells

We report on the temperature-dependent Schottky barrier in organic solar cells based on PTB7:PC71BM. The ideality factor is found to increase with temperature decreasing, which is explained by a model in which the solar cell is taken as Schottky barrier diode. Accordingly, the dark current in the device originates from the thermally emitted electrons across the Schottky barrier. The fittings obtained with the thermal emission theory are systematically studied at different temperatures. It is concluded that the blend/Ca/Al interface presents great inhomogeneity, which can be described by 2 sets of Gaussian distributions with large zero bias standard deviations. With the decrease of temperature, electrons favor going across the Schottky barrier patches with lower barrier height and as a consequence the ideally factor significantly increases at low temperature.

Temperature-Dependent Electrical Characteristics of Ni/Au Vertical Schottky Barrier Diodes on β-Ga2O3 Epilayers

Temperature dependent current transport mechanism in Ni/β-Ga2O3 Schottky Barrier Diodes was studied using current-voltage (I-V) and capacitance-voltage (C-V) characterization techniques in the range of 78–350 K. Schottky barrier height ϕb0 and ideality factor ɳ from I-V characteristics were found to be 1.27 eV and 1.12, respectively, at room temperature. Plots of barrier height and ideality factor with inverse of temperature show strong temperature dependency and a deviation from barrier height obtained from C-V characteristics. The temperature dependence of barrier height and ideality factor assigned to barrier inhomogeneity at Ni/β-Ga2O3 interface, and modulated by the potential fluctuation model. Diode turn-on voltage and turn-on resistance at 300 K were found to be 1.08 eV and 7.80 mΩ-cm2, respectively. A large rectification ratio of the order of 1012 was obtained at room temperature and also the rectification ratio of the order of 109 was consistent over the whole temperature range (78–350 K).

Barrier inhomogeneity in microscale Pt/MoS2 Schottky barrier diode

Temperature dependent electrical characterization of microscopic Pt/MoS2 Schottky diode fabricated using electron beam lithography has been studied. The diode exhibits rectifying current–voltage characteristics in the whole temperature range from room temperature to 80 K. As temperature decreases from 296 to 80 K, Schottky barrier height (SBH) decreases whereas ideality factor increases. The temperature dependence of barrier height of the diode is explained on the basis of barrier inhomogeneity model. Assuming the Gaussian distribution of SBH, the inhomogeneity level is found to be 64 and 102 meV in the temperature regions 80 K–140 K and 160 K–296 K, respectively. The present study can be useful in deeper understanding of electrical behavior of rectifying metal contacts to MoS2.

The ac conductivity of binary chalcogenide glasses $${\text {Se}}_{100-x}{\text {X}}_{x}$$ Se 100 - x X x (X = Ge, In, Te)

The random free energy barrier hopping model is used to investigate the temperature and frequency dependent ac conductivity $$\sigma _{ac}(\omega )$$ of binary chalcogenide glasses $${\text {Se}}_{100-x}{\text {X}}_{x}$$ (X = Ge, In, Te). The temperature dependent barrier height leads to Meyer–Neldel (MN) rule. The calculated MN energy $$E_{MN}$$ is in good agreement with the experimental estimates. The $$\sigma _{ac}(\omega )$$ is taken as the sum of bipolaron and single polaron hopping conductivities $$\sigma _{b}(\omega )$$ and $$\sigma _{s}(\omega ),$$ respectively. The calculated results are in close agreement with the experimental data. It is found that $$\sigma _{s}$$ is smaller by orders of magnitude than $$\sigma _{b}$$ in $${\text {Se}}_{100-x}{\text {Ge}}_{x}$$ alloys in the temperature range 250–400 K, while in $${\text {Se}}_{100-x}{\text {Te}}_{x}$$ alloys $$\sigma _{ac}(\omega )$$ is mainly due to $$\sigma _{b}$$ in the temperature range 150–250 K and $$\sigma _{s}$$ becomes significant above 250 K. However in $${\text {Se}}_{100-x}{\text {In}}_{x}$$ alloys in the temperature range 303–333 K, $$\sigma _{b}$$ is nearly temperature independent and $$\sigma _{ac}(\omega )$$ is mainly due to $$\sigma _{s}.$$ It is found that acoustic phonons assist hopping process in $${\text {Se}}_{100-x}{\text {Ge}}_{x}$$ and $${\text {Se}}_{100-x}{\text {Te}}_{x}$$ alloys, while both high energy acoustic and low energy optical phonons assist hopping process in $${\text {Se}}_{100-x}{\text {In}}_{x}$$ alloys.

Temperature effects on the electrical characteristics of $$\mathrm{Al}/\mathrm{PTh}-\mathrm{SiO}_{2}/\mathrm{p\hbox {-}Si}$$ Al / PTh - SiO 2 / p - Si structure

The temperature-dependent current–voltage (\(I\text {--}V\)) and capacitance–voltage (\(C\text {--}V\)) characteristics of the fabricated Al/p-Si Schottky diodes with the polythiopene–SiO\(_{2}\) nanocomposite (\(\hbox {PTh--SiO}_{2}\)) interlayer were investigated. The ideality factor of \(\hbox {Al}/\hbox {PTh--SiO}_{2}/{p}\text {-Si}\) Schottky diodes has decreased with increasing temperature and the barrier height has increased with increasing temperature. The change in the barrier height and ideality factor values with temperature was attributed to inhomogeneties of the zero-bias barrier height. Richardson plot has exhibited curved behaviour due to temperature dependence of barrier height. The activation energy and effective Richardson constant were calculated as 0.16 eV and \(1.79 \times 10^{-8} \hbox {A\,cm}^{-2} \,\hbox {K}^{-2}\) from linear part of Richardson plots, respectively. The barrier height values determined from capacitance–voltage–temperature (\(C\text {--}V\text {--}T\)) measurements decrease with increasing temperature on the contrary of barrier height values obtained from \(I\text {--}V\text {--}T\) measurements.

Nanostructural, optical and heterojunction characteristics of PEDOT™/ZnO nanocomposite thin films

Poly(3,4-ethylenedioxythiophene), Tetra Methacrylate (PEDOT™)/ZnO nanocomposite thin films were fabricated by the conventional spin coating method and characterized by X-ray diffraction technique. The results indicated that ZnO nanopowder has a polycrystalline nature with a hexagonal system and mean crystallite size of 53.1 nm. The main important optical parameters were extracted by using the spectrophotometer methodology covering the range of 200–2500 nm. A direct allowed transition with the onset and fundamental energy gaps were found to be 1.9 and 3.9 eV. The current density-voltage characteristics of PEDOT™/ZnO nanocomposite film/n-Si heterojunction showed diode-like behavior. Temperature dependence of series and shunt resistances was investigated. The high value of ideality factor (η) can be referred to the influence of an interfacial layer. Temperature dependence of barrier height indicated the presence of inhomogeneous barrier at an interface which is considered to be the reason for the observed behavior of the barrier height with temperature.

Temperature dependence of barrier height in Ni/n-GaN Schottky barrier diode

The temperature dependence of barrier height in a Ni/n-GaN Schottky barrier diode fabricated on a GaN homoepitaxial layer was investigated by capacitance–voltage, current–voltage, and internal photoemission measurements in the range of 223–573 K. The barrier height obtained by these methods linearly decreased with increasing temperature. The temperature coefficient was −(1.7–2.3) × 10−4 eV/K, which is about half of the temperature coefficient of the band gap reported previously. This indicates that the decrease in the barrier height may mainly reflect the shrinkage of the band gap (lowering of the conduction band edge) in GaN with increasing temperature.

Temperature dependent electrical characteristics of Pt Schottky barriers fabricated on lightly and highly doped n-type 4H-SiC

The temperature dependent electronic characteristics of Pt Schottky barriers fabricated on lightly and relatively highly doped n-type 4H-SiC (1 × 1016 and 1 × 1018 cm−3) are comparatively investigated. It is found that the abnormal temperature dependence of barrier height and ideality factor estimated from the thermionic emission (TE) model for both lightly and highly doped samples could be successfully explained in terms of Gaussian distribution of inhomogeneous barrier heights. However, the estimated mean barrier height according to Gaussian distribution for the highly doped sample is much lower than the actual mean value from the capacitance–voltage (C–V) measurements. Interestingly, the values of barrier height from the thermionic field emission (TFE) model are found to be close to those from the C–V measurements, indicating that the TFE model is more appropriate to explain the electrical transport for the highly doped sample.

Simulation to Study the Effect of Carrier Concentration on I-V Characteristics of Schottky Diode

The current-voltage characteristics for Au/n-Si Schottky diode are generated by simulation. The simulation performed using Newton-Raphson iteration method yields current-voltage characteristics over wide temperature range. The data is analyzed using TDE-mechanism to study the temperature dependence of barrier height and ideality factor. Results obtained from simulation studies show the barrier height and ideality factor are independent of temperature for pure TE-mechanism. Thus the simulation of I-V characteristics is performed by incorporating ideality factor, obtained on the basis of carrier concentration from 1022-1024 atoms/m3. The result of analysis yield barrier height is still independent of temperature but the ideality factor becomes temperature dependent and this dependence of ideality factor on temperature increases with increase in carrier concentration. Further, the temperature dependence of barrier height and ideality factor is discussed and simulation of current-voltage characteristics is performed.

Intrinsic inhomogeneity in barrier height at monolayer graphene/SiC Schottky junction

Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties. The inherent spatial inhomogeneity due to the formation of ripples and ridges in graphene can lead to fluctuations in the Schottky barrier height (SBH). The non-ideal behavior of the temperature dependent barrier height and ideality factor greater than 4 can be attributed to these spatial inhomogeneities. Assuming a Gaussian distribution of the barrier, mean SBHs of 1.30 ± 0.18 eV and 1.16 ± 0.16 eV are found for graphene/SiC junctions on the C- and Si-face, respectively. These findings reveal intrinsic spatial inhomogeneities in the SBHs in graphene based Schottky junctions.

Investigation of temperature dependent barrier height of Au/ZnO/Si schottky diodes

In this study, temperature dependent current-voltage (I-V) measurements have been performed to investigate the inhomogeneity in the temperature dependent barrier heights of Au/ZnO/Si Schottky barrier diode in the temperature range 150 – 400K. The room temperature values for ideality factor and barrier height were found to be 2.9 and 0.60 eV respectively indicating the inhomogenity in the barrier heights of grown samples. The Richardson plot and ideality factor verses barrier height graph were also drawn to verified the discontinuity between Au and ZnO. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear Φap (n) plot to n= 1 has given a homogeneous barrier height of approximately 1.1 eV. Φap versus 1/T plot was drawn to obtain the values of mean barrier height for Au/ZnO/Si Schottky diode (1.1 eV) and standard deviation(δs) (0.02 V) at zero bais.

Correction to “Quantitative Extraction of Temperature-Dependent Barrier Height and Channel Resistance of a-SIZO/OMO and a-SIZO/IZO Thin-Film Transistors” [Feb 13 247-249

In the above paper (ibid., vol. 34, no. 2, pp. 247-249, Feb. 2013), the information for corresponding authors is not correctly indicated. Authors S. Kim, S. Y. Lee, and S. W. Hwang are the corresponding authors for this paper. Their information can be found at the bottom of this page.

Temperature Dependence of Barrier Height and Performance Enhancement of Pentacene Based Organic Thin Film Transistor with Bi-Layer MoO3/Au Electrodes

Temperature Dependence of Barrier Height and Performance Enhancement of Pentacene Based Organic Thin Film Transistor with Bi-Layer MoO3/Au Electrodes

Electrical properties of Au/perylene-monoimide/p-Si Schottky diode

Abstract In this work, we have fabricated an Au/perylene-monoimide (PMI)/p-Si Schottky barrier diode. We have investigated how electrical and interface characteristics like current–voltage characteristics (I–V), ideality factor (n), barrier height (ΦB) and series resistance (Rs) of diode change with temperature over a wide range of 100–300 K. Detailed analysis on the electrical properties of structure is performed by assuming the standard thermionic emission (TE) model. Possible mechanisms such as image force lowering, generation–recombination processes and interface states which cause deviations of n values from the unity have been discussed. Cheung–Cheung method is also employed to analysis the current–voltage characteristics and a good agreement is observed between the results. It is shown that the electronic properties of Schottky diode are very sensitive to the modification of perylene-monoimide (PMI) interlayer organic material and also to the temperature. The ideality factor was found to decrease and the barrier height to increase with increasing temperature. The temperature dependence of barrier height shows that the Schottky barrier height is inhomogeneous in nature at the interface. Such inhomogeneous behavior was explained on the basis of thermionic emission mechanism by assuming the existence of a Gaussian distribution of barrier heights.

Temperature dependent ideality factor and barrier height of Ni/n-GaAs/In Schottky diodes

Graphical abstractDisplay Omitted Highlights? Ni/n-GaAs/In Schottky diodes are fabricated by magnetron DC sputtering system. ? The zero-bias barrier height and ideality factor show temperature dependence. ? Temperature dependence of the parameters was attributed to Gaussian distribution in the barrier. ? Temperature dependent flat-band barrier was explained by temperature dependence of band-gap. ? It is recommended that the values of ?s0 and α should be placed on commercial catalogue. Temperature-dependent current-voltage (I-V) characteristics of Ni/n-GaAs/In Schottky diodes which are fabricated by magnetron DC sputtering system have been studied. The zero-bias barrier height (BH) versus temperature plot involves two distinct regions. At low temperatures, the zero-bias BH increases with increasing temperature due to lateral distribution of the barrier height. Werner and Guttler's model has been employed to analyze the temperature dependence of barrier height and ideality factor at low temperatures. The standart deviation of the zero-bias BH was calculated as 64mV and the voltage coefficients of the barrier height were determined as ?2=-6.94i?10-4 and ?3=-5.73mV. At high temperatures, the zero-bias BH decreases with increasing temperature because of the temperature dependence of semiconductor band gap. The non-linearity has been observed in the Richardson plot due to temperature dependence of the zero-bias BH. Furthermore, the T0 effect and the temperature dependence of flat band BH of the diodes were investigated.

Comparative Study of Temperature Dependent Barrier Heights of Pd/ZnO Schottky Diodes Grown along Zn- and O-Faces

In this study, the effect of polar face on Schottky barrier diodes has been investigated. Two samples of ZnO were grown hydrothermally under similar growth conditions. The Palladium (Pd) metal contacts of area 0.78 mm2 were fabricated on both faces and were studied comprehensively using DLS-83 Deep Level Spectrometer over temperature range of 160K330K. The current-voltage (IV) measurements revealed that the ideality factor n and barrier height ϕB were strongly temperature dependent for both faces (Zn and O-face) of ZnO, indicating that the thermionic emission is not the dominant process, which showed the inhomogenity in the barrier heights of grown samples. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear ϕap verses n plot to n = 1 has given a homogeneous barrier height of approximately 0.88±0.01 eV and 0.76±0.01 eV for Zn and O-faces respectively. ϕap versus 1/T plot was drawn to obtain the values of mean barrier height for Zn and O-face (0.88±0.01 eV, 0.76±0.01 eV) and standard deviation (δs) (0.015±0.001 V, 0.014±0.001 V) at zero bais respectively. The value of δs for the Zn-face is larger than O-face, showing that inhomogenity in the barrier heights is more in the sample grown along Zn-face as compared to the sample grown along O-face.