Chemical, electrical and carrier transport properties of Au/cytosine/undoped-InP MPS junction with a cytosine polymer

An Au/cytosine/undoped-InP metal/polymer/semiconductor (MPS) junction was prepared with a cytosine polymer layer by spin coating and e-beam processes. The chemical properties were explored with X-ray photoelectron spectroscopy (XPS) approach and the results confirmed that the cytosine thin film was grown on undoped-InP surface. The electrical properties of MPS were compared with the Au/undoped-InP Schottky junction (SJ) results. Higher barrier height (BH) was achieved for the MPS junction (0.63 eV) than the SJ (0.57 eV), which demonstrates the BH was influenced by the cytosine interlayer. The BH, ideality factor and series resistance of SJ and MPS junction were derived by Chenug's, Norde functions and S-V plot. The derived BH by these three approaches were almost equal with one another that suggests their steadiness and validity. The Poole-Frenkel emission governed the reverse current conduction mechanism in the lower bias region, whereas Schottky emission was ruled in the higher bias region for both the SJ and MPS junction. Analysis demonstrates that such cytosine polymer layers have prospective for use in organic and inorganic electronic devices.