Determination of the characteristic parameters of Sn/n-GaAs/Al–Ge Schottky diodes by a barrier height inhomogeneity model

Abstract

A study on parameters of the Sn/n-GaAs Schottky barrier diode (SBD) fabricated on an n-type GaAs substrate has been made. The Sn/n-GaAs SBD has shown a nearly ideal behaviour with ideality factor and barrier height (BH) values of 1.081 and 0.642 eV, respectively, from the experimental forward-bias current–voltage (I–V) characteristics. A BH value of 0.724 eV has been obtained from the experimental reverse-bias capacitance–voltage (C–V) characteristics. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal–semiconductor interface has been applied. This model attempts to explain abnormal experimental results obtained on ‘real’ Schottky diodes. Our results clearly demonstrate that the electron transport at the metal–semiconductor interface is significantly affected by low-barrier regions (patches). When the experimental data are described by the thermionic emission theory of inhomogeneous Schottky contacts, it has been concluded that both the experimental forward and reverse I–V characteristics and the difference between the values of the experimental I–V and C–V SBHs should be considered. An experimental BH difference of Δ = 0.082 V has been obtained for the Sn/n-GaAs SBD that is less than the critical value; therefore, it has been seen that the potential in front of the patch is not pinched off.