Carbon, especially graphene quantum dots (GQDs) based electronics have become an attractive technology in recent years. The controlled modification of the electrical and optoelectronic properties of GQDs by physical/chemical processes or synthetic methods may lead to new applications. Gadolinium‐doped polyethyleneimine (PEI) functionalized and nitrogen‐doped graphene quantum dots (GdNPs‐PEI@N‐GQDs) are synthesized by a hydrothermal method to determine how doping carbon‐based materials with Gd alters the electrical properties of the structure. The electrical properties of the GdNPs/PEI@N‐GQDs nanocomposite‐based diode are investigated using the current–voltage (I–V) technique and the capacitance and conductance voltage (C–V & G/ω–V) technique at 300 K in the frequency range of 0.5 to 500 kHz at ± 5 V. The rectification ratio (RR) is found to be 14 at a voltage of ±5 V. The rectifying behavior of the diode changes to an ohmic behavior after doping with Gd, compared to the Gd‐free PEI@N‐GQDs sample (2.8 × 10⁴ at ±5 V). The results are expected to have an impact on the understanding of carbon‐based electronics technology.

The Schottky barrier diode is a unipolar electronic device formed by the heterojunction of a metal and a semiconductor, widely used in various electronic and optoelectronic applications. Its rectifying current–voltage characteristic is typically derived using thermionic emission theory, which describes the transport of carriers over the Schottky barrier formed at the metal-semiconductor interface. In this paper, after briefly reviewing the metal-semiconductor heterojunction fundamentals and Landauer’s approach to electric transport, we propose an alternative way to derive the current–voltage behavior of a Schottky diode using Landauer’s formalism. This derivation can be directly applied to Schottky contacts between metals and low-dimensional materials, as demonstrated in the case of a 2D material. Additionally, we extend the proposed approach to account for tunneling currents through the barrier. Finally, we validate our findings with experimental data from a commercial Schottky diode, demonstrating excellent agreement. We also discuss non-ideal effects such as image-force lowering and lateral inhomogeneity of the Schottky barrier. This paper thus proposes an accessible and modern approach to understanding the Schottky diode current–voltage characteristics, making it suitable for both graduate- and postgraduate-level instruction.