Method for Determining the Schottky Diodes Electrical Parameters

Abstract

When studying the operation of Schottky diodes the most important electrical parameters are the height of the potential barrier, the coefficient of ideality, the saturation current and the series resistance of the material and contacts. These parameters can be determined from the experimental volt-ampere characteristics. The article considers the methods of determining these electrical parameters of Schottky diodes, as well as the factors that affect the accuracy of calculations. The existing methods for calculating the electrical parameters of Schottky diodes are analyzed, namely: the method of Norde, Roderick, Chong, Sato and the method of direct approximation. The Norde method was developed for a coefficient of ideality equal to one for cases where the effect of series resistance on the I–V characteristics makes a significant error in determining the barrier height by simpler methods. A significant disadvantage of this method is that in many cases the coefficient of ideality is not equal to one, even in the case of an ideal diode, which makes an error in the calculation result. The advantage of Roderick's method is the possibility of describing the forward and reverse branches of the I–V characteristics by one dependence, as well as taking into account measurements at voltages less than tripled temperature potential. The disadvantages of this method include the lack of consideration of the effect of series resistance, which may result in additional errors. The main advantage of the Chong method is the determination of the series resistance together with the height of the barrier and the coefficient of ideality, which not only provides additional information about the contact, but also convenient in terms of automation of the calculation process. The disadvantages include the possibility of applying the method only to the voltage range above the tripled temperature potential. The disadvantages of Sato methods and direct approximation include the fact that the calculation is performed at one point of the I–V curve, which can negatively affect the accuracy. It is also shown that these methods have a significant standard deviation of the calculated values from the experimental ones, which is due to the temperature dependence of the height of the potential barrier and the dependence of the coefficient of ideality on the voltage. Also, the reason for the increase in the calculation error of the electrical parameters in all five methods is the decrease in the length of the I–V characteristics in logarithmic coordinates. When using any of the considered methods, the calculation is performed in logarithmic coordinates, which complicates the determination of the boundaries of the I–V section, where the dependence of the parameters of the Schottky diode on the voltage is insignificant. A new algorithm for calculating the electrical parameters of Schottky diodes has been developed. Based on the conjugate gradient method, a method for optimizing the algorithm for calculating the electrical parameters of Schottky diodes was developed, which made it possible to reduce the standard deviation by more than an order of magnitude. The developed algorithm is verified by comparing the calculated volt-ampere characteristics of Schottky diodes with those obtained experimentally. To construct the calculated volt-ampere characteristics, the values of the electrical parameters of Schottky diodes were used, which were determined by the presented algorithm. The results of the calculation are in good agreement with the experimental data. The proposed method can be used both in scientific work to study the properties of semiconductor materials, and in production to control the quality of Schottky diodes.