Surface related tunneling leakage in β-Ga₂O₃ (001) vertical Schottky barrier diodes

Abstract

β-Ga2O3 (001) Schottky barrier diodes (SBDs) fabricated on a halide vapor phase epitaxy-grown epilayer showed anomalous reverse leakage characteristics, which could not be explained through thermionic field emission theory. A systematic investigation through the measurements and simulations of capacitance-voltage and current density-voltage characteristics suggested the presence of a thin surface layer on the epilayer with high density of oxygen vacancy states. This thin surface layer allowed the tunneling of electrons and caused anomalous reverse leakage properties (Thin surface barrier model). Annealing of the epilayer in an oxidative environment passivated the surface oxygen vacancy states and reduced the reverse leakage current enormously.

Barrier reduction and current transport mechanism in Pt/n-InP Schottky diodes using atomic layer deposited ZnO interlayer

“…To explain the abnormally large reverse leakage current in GaN Schottky diodes, Hashizume et al suggested that a thin surface barrier (TSB) formed by surface defects in the surface layer can induce significant tunneling leakage current [57]. Lingaparthi et al also employed such TSB model to explain the reverse leakage current in Ga 2 O 3 -based Schottky diode [58]. By varying the ALD growth conditions, we can modify the carrier concentration of ZnO layer and the thin ZnO layer can act as a TSB.…”

Reduction of Fermi-Level Pinning and Controlling of Ni/β-Ga2O3 Schottky Barrier Height Using an Ultrathin HfO2 Interlayer

“…For direct tunneling mechanism model, the tunneling current can be given by − J normalT = A * T normalL K normalB ∫ ϵ ∞ normalΓ ( E ′ ) .25em ln ( 1 + F s false( E ′ false) 1 + F m false( E ′ false) ) .25em normald E ′ where A * is the Richardson’s constant with a value of 41.11 A cm –2 K –2 , K B is the Boltzmann constant, F s ( E ′) and F m ( E ′) are the Maxwell–Boltzmann distribution in the metal and the semiconductor, respectively, and Γ( E ′) is the tunneling probability.…”

Control and understanding of metal contacts to β-Ga2O3 single crystals: a review

“…The density of surface states for epi-1 sample was found to be higher than those for bulk and epi-2 samples, indicating the presence of higher density of V O -related states on the β-Ga 2 O 3 surface for epi-1 sample. In another work [77], they showed by simulation that deep donor type surface states (probably V O ) are responsible for lowering the barrier height and increasing the reverse leakage current. Based on the results they suggested that the oxygen vacancy generated in (001) β-Ga 2 O 3 epitaxial layer during the HVPE growth process affected on the SBH and the electrical properties of (001) β-Ga 2 O 3 based devices.…”

“…/doi.org/10.1007/s42452-021-04895-9 on ( 2 01) and (010) substrates, Fu et al showed that the reverse current for both samples were explained by the TAT and 1D-VRH models[21].Lingaparthi et al observed high reverse leakage current in Ni/(001) β-Ga 2 O 3 Schottky diodes[77]. Based on the comparison between experimental and simulation data, they concluded that the thin surface barrier formed by high density of oxygen vacancies near the surface caused tunneling to occur easily.…”