Temperature-dependent charge transport and double gaussian barrier inhomogeneity in Au/PDI/n-Ge schottky diodes
摘要
An Au/PDI/n-Ge Schottky diode with a perylene diimide (PDI) organic interlayer was fabricated and its electrical behavior was investigated over the temperature range of 100–350 K. AFM analysis revealed a continuous yet non-uniform surface with nanoscale island-like features, indicating interfacial inhomogeneity. Temperature-dependent I–V characteristics exhibited strong rectification, while the barrier height increased and the ideality factor decreased with temperature, clearly deviating from ideal thermionic emission (TE). This deviation was rigorously analyzed using a double Gaussian distribution (GD) model, revealing two distinct barrier regimes associated with localized low-barrier patches embedded in a higher background barrier, consistent with inhomogeneous Schottky interfaces. The extracted mean barrier heights (~ 0.59 eV and ~ 1.004 eV) confirm spatial barrier fluctuations governing carrier transport. Modified Richardson analysis yielded values close to the theoretical constant, validating the GD-assisted TE model. Current transport analysis demonstrated a transition from ohmic conduction to trap-controlled and trap-free space-charge-limited current (SCLC), while reverse bias behavior was dominated by Schottky emission. Interface state density (