Dec 16, 2014

Temperature dependence of current-and capacitance–voltage characteristics of an Au/4H-SiC Schottky diode


I have fabricated an Au/4H-SiC Schottky diode in optimum conditions.
The abnormal behaviors observed at low temperatures are related to Schottky barrier inhomogeneities.
The barrier abnormality can be successfully commented by both multi-Gaussian distribution model and pinch-off model.
Thus, it is noted that multi-Gaussian distribution model is good agreement with pinch-off model to interpret abnormalities.

In this study, the current–voltage (IV) and capacitance–voltage (CV) measurements of an Au/4H-SiC Schottky diode are characterized as a function of the temperature in 50–300 K temperature range. The experimental parameters such as ideality factor and apparent barrier height presents to be strongly temperature dependent, that is, the ideality factor increases and the apparent barrier height decreases with decreasing temperature, whereas the barrier height values increase with the temperature for CV data. Likewise, the Richardson plot deviates at low temperatures. These anomaly behaviors observed for Au/4H-SiC are attributed to Schottky barrier inhomogeneities. The barrier anomaly which relates to interface of Au/4H-SiC is also confirmed by the CV measurements versus the frequency measured in 300 K and it is interpreted by both Tung’s lateral inhomogeneity model and multi-Gaussian distribution approach. The values of the weighting coefficients, standard deviations and mean barrier height are calculated for each distribution region of Au/4H-SiC using the multi-Gaussian distribution approach. In addition, the total effective area of the patches NAe is obtained at separate temperatures and as a result, it is expressed that the low barrier regions influence meaningfully to the current transport at the junction. The homogeneous barrier height value is calculated from the correlation between the ideality factor and barrier height and it is noted that the values of standard deviation from ideality factor versus q/3kT curve are in close agreement with the values obtained from the barrier height versus q/2kT variation. As a result, it can be concluded that the temperature dependent electrical characteristics of Au/4H-SiC can be successfully commented on the basis of the thermionic emission theory with both models.


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