Series resistance calculation for the Metal-Insulator-Semiconductor Schottky barrier diodes

Abstract

An accurate way of determining the series resistance R_s of Schottky Barrier Diodes (SBDs) with and without the interfacial oxide layer using forward current-voltage (I–V) characteristics is discussed both theoretically and experimentally by taking into account the applied voltage drop across the interfacial layerV _i. For the experimental discussion, the forward biasI–V characteristics of the SBDs with and without the oxide layer fabricated by LEC (the Liquid-Encapsulated Czochralski) GaAs were performed. The SBD without the oxide layer was fabricated to confirm a novel calculation method. For the theoretical discussion, an expression ofV _i was obtained by considering effects of the layer thickness and the interface state density parameters on forward biasI–V of the SBDs. The valueR _s of the SBD with interfacial oxide layer was seen to be larger than that of the SBD without the interfacial oxide layer due to contribution of this layer to the series resistance. According to the obtained theoretical formula, the value ofV _i for the SBD with the oxide layer was calculated and it was subtracted from the applied voltage values V and then the value ofR _s was recalculated. Thus, it has been shown that this new value ofR _s is in much closer agreement with that determined for the SBD without the oxide layer as predicted. Furthermore, the curves of the interface states energy distribution of each sample are determined. It was concluded that the shape of the density distribution curve and order of magnitude of the density of the interface states in the considered energy range are in close agreement with those obtained by others for Au/n-GaAs Schottky diodes by Schottky capacitance spectroscopy.