A study of temperature dependent current–voltage (I–V–T) characteristics in Ni/sol–gel β-Ga₂O₃/n-GaN structure

β-Ga₂O₃ thin films were grown on n-type GaN substrates using the sol–gel method. The forward-biased temperature dependent current–voltage (I–V–T) characteristics of Ni/β-Ga₂O₃/GaN structure have been investigated in the temperature range of 298–473 K. The apparent barrier height (\({\phi _{ap}}\)) increased while the ideality factor (n) decreased with the increase in temperature. Such a temperature dependent behavior of \({\phi _{ap}}\) and n was explained by the inhomogeneity of \({\phi _{ap}}\), which obeyed Gaussian distribution with zero-bias mean barrier height (\({\bar {\phi }_{B0}}\)) of 1.02 ± 0.02 eV and standard deviation (\({\sigma _{s0}}\)) of 153 ± 0.04 mV. Subsequently, \({\bar {\phi }_{B0}}\) and Richardson constant A^* were obtained from the slope and intercept of the modified Richardson plot as 0.99 ± 0.01 e V and 67.2 A cm⁻² K⁻², respectively. The \({\bar {\phi }_{B0}}\) obtained from the modified Richardson plot was in good agreement with the theoretical value calculated from the work function of Ni and electron affinity of β-Ga₂O₃. The I–V–T characteristics of Ni/β-Ga₂O₃/GaN MOS structures can be successfully explained by the thermionic emission theory with a single Gaussian distribution of the barrier height.