Temperature and voltage dependence of barrier height and ideality factor in Au/0.07 graphene-doped PVA/n-Si structures

Abstract

In this study, Au/0.07 graphene-doped PVA/n-Si structures were fabricated and current conduction mechanism in these structures were investigated in the temperature range of 80–380 K through forward bias current–voltage (I–V) measurements. Main electrical parameters were extracted from I–V data. Zero-bias barrier height ($\overline{\varPhi }_{B0}$) and ideality factor (n) were found strong functions of temperature and their values ranged from 0.234 eV and 4.98 (at 80 K) to 0.882 eV and 1.15 (at 380 K), respectively. Φ _ap versus q/2kT plot was drawn to obtain an evidence of a Gaussian distribution of the barrier heights (BHs) and it revealed two distinct linear regions with different slopes and intercepts. The mean values of BH (Φ _Bo) and zero-bias standard deviation (σ _s ) were obtained from the intercept and slope of the linear regions of this plot as 1.30 eV and 0.16 V for the first region (280–380 K) and 0.74 eV and 0.085 V for the second region (80–240 K), respectively. Thus, the values of $\overline{\varPhi }_{B0}$ and effective Richardson constant (A*) were also found from the intercept and slope of the modified Richardson plot [ln(I _s /T ²) − q ² σ ² _o /2k ² T ² vs q/kT] as 1.31 eV and 130 A/cm² K² for the first region and 0.76 eV and 922 A/cm² K² for the second region, respectively. The value of A* for the first region was very close to the theoretical value for n-Si (112 A/cm² K²). The energy density distribution profile of surface states (N_ss) was also extracted from the forward bias I–V data by taking into account voltage dependent effective BH (Φ_e) and n.