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

Abstract

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.