Schottky Barrier Height Dependence on the Metal Work Function for p-type Si Schottky Diodes (original) (raw)
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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.
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.
Annealing temperature effect on electrical characteristics of Co/p-type Si Schottky barrier diodes
Physica B: Condensed Matter, 2009
The electrical characteristics of Co/p-type Si Schottky barrier diodes (SBDs), which were formed at various annealing temperatures from 200 to 600 1C, were investigated using current-voltage (I-V) techniques. The Schottky barrier height at 200 1C annealing temperature was found to be 0.708 eV (I-V). However, the Schottky barrier height of the Co/p-type Si diode slightly decreases to 0.696 eV (I-V) when the diode was annealed at 300 1C for 5 min in N 2 atmosphere. It is noted that the Schottky barrier height increased to 0.765 eV at 400 1C, 0.830 eV at 500 1C and 0.836 eV at 600 1C for 5 min in N 2 atmosphere. This increase was attributed to that the annealing removes the passivation effect of the native oxide layer and reactivates the surface defects which are responsible for the Fermi level pinning. Norde method was also used to extract the barrier height of Co/p-type Si Schottky barrier diodes and the values are 0.704 eV for the 200 1C, 0.714 eV at 300 1C, 0.80447 eV at 400 1C, 0.874 eV at 500 1C and 0.874 eV at 600 1C which are in good agreement with those obtained by the I-V method.
International Journal of Electronics, 2018
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 (I o), ideality factors (n), barrier heights (Ф bo), rectification ratio (RR) and series resistances (R S) were obtained from I-V and C-V measurements using different 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 (N SS) as a function of energy distribution (E SS-E V) was obtained from the I-V data by taking into account the bias dependence of the effective barrier height (Φ b) for the Re/n-type Si Schottky barrier diodes.
Comparison of electrical parameters of Zn/p-Si and Sn/p-Si Schottky barrier diodes
Solid State Communications, 2005
In this study, current-voltage (I-V) and capacitance-voltage (C-V) characteristics of metal-semiconductor (MS) Zn/p-Si and Sn/p-Si Schottky diodes, with high resistivity silicon structures, are investigated. The parameters of series resistance (R S), the ideality factor (n) and the barrier height (F b) are determined by performing different plots from the forward bias current-voltage (I-V) and reverse bias capacitance-voltage (C-V) characteristics. Thus, the barrier heights (F b) for the Si Schottky diodes obtained between 0.725 and 1.051 eV, the ideality factor (n) between 1.043 and 1.309, and the series resistance (R S) between 12.594 and 12.950 kU. The energy distribution of interface states density was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. It was concluded that the density of interface states in the considered energy range are in close agreement with each other values obtained for Zn/p-Si and Sn/p-Si Schottky diodes.
Determination of the laterally homogeneous barrier height of metal/p-InP Schottky barrier diodes
Vacuum, 2009
We have reported a study of a number of metal/p-type InP (Cu, Au, Al, Sn, Pb, Ti, Zn) Schottky barrier diodes (SBDs). Each one diode has been identically prepared on p-InP under vacuum conditions with metal deposition. In Schottky diodes, the current transport occurs by thermionic emission over the Schottky barrier. The current-voltage characteristics of Schottky contacts are described by two fitting parameters such as effective barrier height and the ideality factor. Due to lateral inhomogeneities of the barrier height, both characteristic diode parameters differ from one diode to another. We have determined the lateral homogeneous barrier height of the SBDs from the linear relationship between experimental barrier heights and ideality factors that can be explained by lateral inhomogeneity of the barrier height. Furthermore, the barrier heights of metal-semiconductor contacts have been explained by the continuum of metal-induced gap states (MIGS). It has been seen that the laterally homogeneous barrier heights obtained from the experimental data of the metal/p-type InP Schottky contacts quantitatively confirm the predictions of the combination of the physical MIGS and the chemical electronegativity.
Interface structure and Schottky barriers at epitaxial Si(111)/Pb interfaces
Surface Science Letters, 1991
Two different epitaxial Si(Ill)/Pb interfaces can be prepared. i.e. a metastable interface with a (7 x 7) and a stable interface with an incommensurate but close to (& X fi)R30° surface unit cell. Schottky barrier heights of diodes made by depositing thick Ph layers on these interfaces are very dependent on the structure at the interface (0.70 and 0.93 eV for the (7 x 7) and (6 x fi)R30° type interfaces respectively). In particular the second value is very exceptional for metal-silicon contacts. Even higher values were found from shifts in photoelectron spectra of Si covered with one ML (0.94 and 1.04 eV respectively). Evidence from ARUPS data indicates that the corresponding pinning level is associated with a discrete interface state in a common gap of Ph and Si.
Applied Physics Letters, 2011
The low temperature electrical behavior of adjacent silicide/Si Schottky contacts with or without dopant segregation is investigated. The electrical characteristics are very well modeled by thermionic-field emission for nonsegregated contacts separated by micrometer-sized gaps. Still, an excess of current occurs at low temperature for short contact separations or dopant-segregated contacts when the voltage applied to the device is sufficiently high. From two-dimensional self-consistent nonequilibrium Green's function simulations, the dependence of the Schottky barrier profile on the applied voltage, unaccounted for in usual thermionic-field emission models, is found to be the source of this deviation.
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.