Enhanced Rectification of Lanthanum Hydroxide‐Doped Graphene Quantum Dots/Silicon Heterostructures at Cryogenic Temperatures

This study reports the fabrication and temperature-dependent electrical characterization of a heterojunction formed by lanthanum(III) hydroxide nanoparticles doped with polyethyleneimine-functionalised nitrogen-doped graphene quantum dots(La(OH) 3 NPs/PEI N-GQDs) on n-type silicon (n-type Si). The heterostructure exhibits diode-like behaviour in the 77–400 Ktemperature range, with rectification exceeding two orders of magnitude and increasing as the temperature decreases, reaching anexceptionally high value above 105 at 77 K. Temperature-dependent diode parameters, including barrier height, series resistance,and ideality factor, are extracted using the thermionic emission model, revealing that barrier height increases and ideality factordecreases with rising temperature. These trends, along with significant deviations from the ideal Richardson behaviour of Schottkydiodes, are effectively explained by the Werner–Güttler model, which attributes them to Gaussian spatial inhomogeneities ofthe barrier arising from interface states and nanocomposite-induced fluctuations. This study highlights the robust rectifyingbehaviour, excellent cryogenic performance, and wide-temperature applicability of the La(OH)3 NPs/PEI N-GQDs on the Siheterostructure, establishing it as a promising platform for low-power diode applications under extreme thermal conditions.