Determination of Contact Parameters of Au/n-Ge Schottky Barrier Diode with Rubrene Interlayer

Öz

Electrical characterization of an Au/n-Ge semiconductor Schottky diode with organic (rubrene) interface has been systematically carried out over a wide temperature range. In sample fabrication stage, first, the ohmic In contact has been performed on one surface of n-Ge wafer grown in direction of (100). Later, the other surface of the wafer has been coated with rubrene by spin-coating method and then the Schottky contact has been constituted on the organic material via thermal evaporation method. The current-voltage (I-V) characteristics of prepared Schottky diode has been measured at a temperature range of 150-300 K and it has been observed that the diode have a rather good rectification behavior at all temperature. By using the I-V characteristics, the idealite factor, barrier height and some other diode parameters have been calculated for all temperatures. These parameters have also been calculated by means of Cheung-Cheung method. Werner and Güttler’s model has been employed to analyze the temperature dependence of barrier height and ideality factor at low temperatures. The standard deviation of the zero-bias barrier height was calculated as 120 mV and the voltage coefficients of the barrier height were determined as 𝜌2 = 0.184 and 𝜌3 = 0.232 mV. At high temperatures, the zero-bias barrier height 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 barrier height. Richardson constant was determined by using different methods. Of the current-voltage analysis’s has emerged an abnormal decrease of apparent barrier height and increase of ideality factor at low temperature. It is determined that these abnormalies result due to the barrier height inhomogeneities prevailing at the organic-semiconductor interface. As a result, homogeneities in Au/rubrene/n-Ge Schottky barrier diode can be successfully characterized by a Gaussian distribution.

Anahtar Kelimeler

• Schottky Contacts,Rubrene Thin Film,Gaussian Distribution,Inhomogeneities

Kaynakça

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