Carrier transport across PtSe₂/n-type GaN heterojunction

We fabricated PtSe₂/n-type GaN heterojunction diode by transferring a large-scale grown two-dimensional (2D) PtSe₂ layered film onto a 3D GaN substrate. The PtSe₂ film transferred onto GaN was ∼5.84-nm thick and had 11 layers with interlayer spacing of 0.52 nm. An exploration of the temperature-dependence of the current–voltage (I–V) characteristics of the PtSe₂/n-type GaN heterojunction in the range 125–400 K revealed a strong dependency of the ideality factor and barrier height on measurement temperature. This indicates a presence of low- and high-barrier-height patches resembling barrier inhomogeneities along the interface. A barrier inhomogeneity analysis with a consideration for the Gaussian barrier heights distribution demonstrated the existence of a double Gaussian barrier distribution having a mean barrier height of 0.97 and 1.41 eV in low- and high-temperature regimes, respectively. An examination of the temperature-dependency of reverse leakage current indicated the dominance of variable-range hopping conduction in lower temperature region (<225 K) and Poole–Frenkel emission mechanism in higher temperature region (>250 K). The interface state density N_ss of the PtSe₂/n-type GaN heterojunction determined from the capacitance method was lesser than that attained from the forward I–V characteristics that can be accredited to the inhomogeneous spreading of the N_ss.