The explanation of barrier height inhomogeneities in Au/n-Si Schottky barrier diodes with organic thin interfacial layer (original) (raw)
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Materials Science in Semiconductor Processing, 2014
The current-voltage (I-V) measurements on Al/ZnS Schottky barrier diodes in the temperature range 303-423 K by the step of 15 K were carried out. The forward I-V characteristics were analyzed on the basis of the thermionic emission theory. The temperature dependence I-V parameters such as ideality factor (n) and barrier height ( b0) have been explained on the basis of inhomogeneity. An abnormal increase of apparent barrier height and decrease of ideality factor with increasing temperature have been explained due to the barrier height inhomogeneities on the basis of the thermionic emission theory with Gaussian distribution. Experimental results reveal the existence of a single Gaussian distribution with apparent barrier height value () of 1.091 eV and standard deviations ( s) of 0.18 V. Richardson constant (A*) was obtained as 8.49 x 10-2 A.m-2 K-2 from the ln(I 0 /T 2) vs. q/kT plot, which is far from the calculated value of 5.6 x 10 5 A.m-2 K-2. The modified Richardson plotof ln(I 0 /T 2)-(q 2 s 2 /2k 2 T 2) gives and A* values as 1.093 eV and 6.07 x 10 5 A.m-2 K-2 , without using the temperature coefficient of the barrier height. This obtained value of A* is extremely close to the previously calculated value. So, the temperature dependence of the forward bias I-V characteristics of the Schottky device can be successfully explained on the basis of the thermionic emission mechanism with a single Gaussian distribution of the barrier heights.
The barrier height inhomogeneity in Al/p-Si Schottky barrier diodes with native insulator layer
Applied Surface Science, 2006
The current-voltage (I-V) characteristics of Al/p-Si Schottky barrier diodes (SBDs) with native insulator layer were measured in the temperature range of 150-375 K. The estimated zero-bias barrier height F B0 and the ideality factor n assuming thermionic emission (TE) theory show strong temperature dependence. Evaluation of the forward I-V data reveals an increase of zero-bias barrier height F B0 but decrease of ideality factor n with increase in temperature. The conventional Richardson plot exhibits non-linearity below 250 K with the linear portion corresponding to activation energy of 0.41 eV and Richardson constant (A *) value of 1.3 Â 10 À4 A cm À2 K À2 is determined from intercept at the ordinate of this experimental plot, which is much lower than the known value of 32 A cm 2 K 2 for holes in p-type Si. Such behavior is attributed to Schottky barrier inhomogene ties by assuming a Gaussian distribution of barrier heights (BHs) due to barrier height inhomogeneities that prevail at interface. Also, F B0 versus q/2kT plot was drawn to obtain evidence of a Gaussian distribution of the BHs, and values of F B0 = 1.055 eV and s 0 = 0.13 V for the mean BH and zero-bias standard deviation have been obtained from this plot, respectively. Thus, the modified ln ðI 0 =T 2 Þ À q 2 s 2 o =2k 2 T 2 versus q/kT plot gives F B0 and A * as 1.050 eV and 40.08 A cm À2 K À2 , respectively, without using the temperature coefficient of the barrier height. This value of the Richardson constant 40.03 A cm À2 K À2 is very close to the theoretical value of 32 A K À2 cm À2 for p-type Si. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Al/p-Si Schottky barrier diodes with native insulator layer can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights.
Applied Physics A, 2017
In this paper, we report the preparation and characterization of SnO 2-PVA nanocomposite film as interlayer for Schottky barrier diodes (SBDs). The possible current transport mechanisms (CTMs) of the prepared SBDs were investigated using the forward-bias currentvoltage (I-V) characteristics in the temperature range of 80-400 K. The structure of nanocomposite film was characterized by an X-ray diffractometer (XRD) and the surface morphology was investigated using a Scanning Electron Microscopy (SEM) at room temperature. The values of ideality factor (n) and zero-bias barrier height (U Bo) showed variation with temperature, such that they changed from 19.10 to 3.77 and 0.190 to 0.844 eV, respectively. U Bo-n, U Bo −q/2kT, and n −1 −q/2kT plots were drawn to get evidence to the Gaussian Distribution (GD) of the barrier height (BH). These plots revealed two distinct linear regions with different slopes for low temperatures (80-160 K) (LTs) and high temperatures (180-400 K) (HTs). This behavior is an evidence to the existence double GD of BHs which provides an average value for BH (U Bo) and a standard deviation (σ s) for each region. The high value of n especially at low temperatures was attributed to the existence of interlayer: interface states (N ss) and barrier inhomogeneity at Au/n-Si interface. The values of U Bo and σ s were obtained from the intercept and slope of mentioned plots as 0.588 and 0.0768 V for LTs and 1.183 eV and 0.158 V for HTs, respectively. Moreover, the modified ln (I s /T 2)−q 2 σ s 2 /2k 2 T 2 vs q/kT plot also showed two linear regions. The values of U Bo and effective Richardson constant (A *) were extracted from the slope and intercept of this plot as 0.610 eV and 93.13 A/cm 2 K 2 for LTs and 1.235 eV and 114.65 A/cm 2 K 2 for HTs, respectively. The value of A * for HTs is very close to the theoretical value (112 A/cm 2 K 2) of n-type Si. Thus, the forward-bias I-V-T characteristics of Au/SnO 2-PVA/n-Si (SBDs) were successfully explained in terms of the thermionic-emission (TE) mechanism with a double GD of BHs.
Gaussian distribution of inhomogeneous barrier height in Ag/p-Si (100) Schottky barrier diodes
Applied Surface Science, 2004
The current-voltage (I-V) measurements on Ag/p-Si Schottky barrier diodes in the temperature range 125-300 K were carried out. The I-V analysis based on the thermionic emission (TE) theory has revealed an abnormal decrease of apparent barrier height and increase of ideality factor at low temperature. It is demonstrated that these anomalies result due to the barrier height inhomogeneities prevailing at the metal-semiconductor interface. A F b0 versus q=2kT plot was drawn to obtain evidence of a Gaussian distribution of the barrier heights, and values of F b0 ¼ 0:780 eV and s s0 ¼ 0:0906 V for the mean barrier height and standard deviation at zero bias have been obtained from this plot, respectively. Furthermore, the mean barrier height and the Richardson constant values were obtained as 0.773 eV and 15.53 A K À2 cm À2 , respectively, by means of the modified Richardson plot, lnðI 0 =T 2 Þ À ðq 2 s 2 s0 =2k 2 T 2 Þ versus 1000/T. Thus, it has been concluded that the temperature dependence of the I-V characteristics of the Schottky barrier on p-type Si can be successfully explained on the basis of thermionic emission mechanism with Gaussian distribution of the barrier heights. Moreover, the value of the Richardson constant was found to be 15.53 A K À2 cm À2 , which is close to the theoretical value of 32 A K À2 cm À2 used for the determination of the zero-bias barrier height.
Current transport mechanism in Al/Si3N4/p-Si (MIS) Schottky barrier diodes at low temperatures
Applied Surface Science, 2006
The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of metal-insulator-semiconductor (Al/Si 3 N 4 /p-Si) Schottky barrier diodes (SBDs) were measured in the temperature range of 80-300 K. By using the thermionic emission (TE) theory, the zero-bias barrier height F B0 calculated from I-V characteristics was found to increase with increasing temperature. Such temperature dependence is an obvious disagreement with the negative temperature coefficient of the barrier height calculated from C-V characteristics. Also, the ideality factor decreases with increasing temperature, and especially the activation energy plot is nonlinear at low temperatures. Such behaviour is attributed to Schottky barrier inhomogeneties by assuming a Gaussian distribution of barrier heights (BHs) at interface. We attempted to draw a F B0 versus q/2kT plot to obtain evidence of a Gaussian distribution of the BHs, and the values of F Bo = 0.826 eV and a o = 0.091 V for the mean barrier height and standard deviation at zero-bias, respectively, have been obtained from this plot. Thus, a modified ln(I o /T 2) À q 2 s o 2 /2(kT) 2 versus q/kT plot gives F B0 and Richardson constant A * as 0.820 eV and 30.273 A/cm 2 K 2 , respectively, without using the temperature coefficient of the barrier height. This value of the Richardson constant 30.273 A/cm 2 K 2 is very close to the theoretical value of 32 A/cm 2 K 2 for p-type Si. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Al/Si 3 N 4 /p-Si Schottky barrier diodes can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights. In addition, the temperature dependence of energy distribution of interface state density (N SS) profiles was determined from the forward I-V measurements by taking into account the bias dependence of the effective barrier height and ideality factor.
Journal of Applied Physics, 2011
In this study, the forward and reverse bias current-voltage (I-V) characteristics of Au/Zinc acetate doped polyvinyl alcohol/n-Si Schottky barrier diodes (SBDs) have been investigated over the temperature range of 80-400 K. The values of zero-bias barrier height evaluated from forward and reverse bias I-V data, (A BFo ) and (A BRo ), increase with increasing temperature, and a discrepancy is observed between the values of A BFo and A BRo . Because the apparent barrier height (BH) seen from metal to semiconductor is higher than the one seen from semiconductor to metal, the obtained value of A BFo is always greater than A BRo value. The difference between them is almost the same as the Fermi energy level. The crossing of the experimental forward bias semilogarithmic ln I-V plots appears as an abnormality when compared to the conventional behavior of ideal SBDs. This behavior was attributed to the lack of free charge at a low temperature and could be expected in the temperature region where there is no carrier freezing out, which is non-negligible at low temperatures. Prior to intersection, the voltage dependent value of resistance (R i ) obtained from Ohm's law decreases with increasing temperature, but it begins to increase after this intersection point. Such an increase in A Bo and series resistance (R s ) with temperature corresponding to high voltage region is in obvious disagreement with the reported negative temperature coefficients. However, the value of shunt resistance (R sh ) corresponding to a low or negative voltage region decreases with increasing temperature. In addition, the temperature dependent energy density distribution profiles of interface states (N ss ) were obtained from forward bias I-V measurements by taking into account the bias dependence of the effective barrier height (A e ) and R s of the device, and the values of N ss without considering R s are almost one order of magnitude larger than N ss when considering R s value.
Microelectronics Reliability, 2011
The current-voltage (I-V) characteristics of Al/p-Si Schottky barrier diode (SBD) with native insulator layer were measured in the temperature range of 178-440 K. The estimated zero-bias barrier height U Bo and the ideality factor n assuming thermionic emission (TE) theory have shown strong temperature dependence. Evaluation of the forward I-V data have revealed an increase of zero-bias barrier height U Bo but the decrease of ideality factor n with the increase in temperature. The experimental and theoretical results of the tunneling current parameter E o against kT/q were plotted to determine predominant current-transport mechanism. But the experimental results were found to be disagreement with the theoretical results of the pure TE, the thermionic-field emission (TFE) and the field emission (FE) theories. The conventional Richardson plot has exhibited non-linearity below 240 K with the linear portion corresponding to the activation energy of 0.085 eV and Richardson constant (A Ã) value of 2.48 Â 10 À9 A cm À2 K À2 which is much lower than the known value of 32 A cm À2 K À2 for holes in p-type Si. Such behaviours were attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (BHs) due to barrier height inhomogeneities that prevail at interface. Thus, the modified ln(I o /T 2) À q2ro2/2k 2 T 2 vs q/kT has plotted. Then A Ã was calculated as 38.79 A cm À2 K À2 without using the temperature coefficient of the barrier height. This value of the Richardson constant 38.79 A cm À2 K À2 is very close to the theoretical value of 32 A K À2 cm À2 for p-type Si. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Al/p-Si Schottky barrier diodes with native insulator layer can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights.
Current-voltage (I-V) characteristics of Au/PVA(Co,Ni-doped)/n-Si (111) SBDs have been investigated in the temperature range of 280-400 K. The zero-bias barrier height (ΦB0) and ideality factor (n) determined from the forward bias I–V characteristics were found strongly depend on temperature. The forward bias semi-logarithmic I-V curves for the different temperatures have an almost common cross-point at a certain bias voltage. While the value of n decreases, the ΦB0 increases with increasing temperature. Therefore, we attempted to draw a Φbo vs q/2kT plot to obtain evidence of a Gaussian distribution of the barrier heights, and to calculate the values of mean barrier height and standard deviation at zero bias, respectively.
Silicon, 2020
The electrical properties have been investigated for Ni/Ta 2 O 5 /p-Si Metal/insulator/semiconductor SBD in the temperature regime 175-400 K. The electrical parameters were analyzed using current-voltage characteristics as a function of operating temperature. It is observed that the Schottky barrier height increased whereas ideality factor and series resistance decreased with increasing the operating temperature. The characteristic temperature (T o) value calculated from Norde and Cheung methods was compared. This analysis showed that T o value extracted from both the techniques are in close agreement with each other. Experimental results revealed that the thermal coefficient was −4.5 mV/K. The Gaussian distribution of the barrier height was estimated from the plot of zero-bias barrier height (Φ bo) versus 1/2kT plot and the estimated value of (Φ bo) of 0.92 eV and 0.79 eV with standard deviation (σ 0) of 0.023 V and 0.014 V, respectively. The mean BH and the Richardson constant values were determined using ln (I o /T 2)-q 2 σ 2 0 /2(kT) 2 versus 1000/T plot and were 0.89 eVand 0.76 eVand 30.03 and 26.85 A/cm −2 K −2 , respectively. In addition to the thermionic emission process, two more conduction mechanisms such as Poole-Frenkel emission in the temperature regime 175-275 K and Schottky emission dominant beyond 300 K temperature were noticed.