Frequency‐Dependent Capacitance and Conductance Characteristics of Ag/n‐GaAs Schottky Diodes With a Perylene‐Monoimide Organic Interlayer

A perylene‐monoimide (PMI) organic semiconductor was used as a spin‐coated interfacial layer in an Ag/PMI/n‐GaAs/In Schottky diode fabricated on (100)‐oriented n‐type GaAs. The frequency‐dependent capacitance–voltage ( C – V ) and conductance–voltage ( G – V ) characteristics were investigated at room temperature in the dark from 50 kHz to 1 MHz over the bias range −3 to +3 V. AFM analysis revealed a homogeneous PMI film with low surface roughness, indicating successful interface engineering and stable film formation on the n‐GaAs surface. The C – V curves exhibited the inversion–depletion–accumulation behavior typical of MIS‐type structures, confirming that the PMI layer modifies the Ag/n‐GaAs contact into an organic‐assisted MIS configuration. The series resistance extracted by the Nicollian–Brews method decreased systematically with increasing frequency, and the corrected admittance recovered the intrinsic MIS response. From the C −2 – V analysis, the apparent barrier height rose from 1.41 eV at 50 kHz to 1.63 eV at 1 MHz, while the donor concentration remained at about 8 × 10 15 cm −3 . The frequency dispersion is attributed to the response of interface states at the PMI/n‐GaAs boundary. The PMI interlayer therefore offers a promising route to interface engineering of high‐frequency GaAs‐based Schottky and optoelectronic devices.