On double exponential forward bias current-voltage (I–V) characteristics of Au/Ca₃Co₄Ga_0.001O_x/n-Si/Au (MIS) type structures in temperature range of 80–340 K

Abstract

Current transport mechanisms (CTMs) of Au/Ca₃Co₄Ga_0.001O_x/n-Si/Au (MIS) type structures were investigated using current–voltage (I–V) characteristics in the temperature range of 80–340 K. Semilogarithmic I–V plots show two linear regions corresponding to low (0.075–0.250 V) and moderate (0.27–0.70 V) biases, respectively. Zero-bias barrier height (Φ_B0) was observed to increase with increase in the temperature, whereas opposite behaviour was observed for ideality factor (n). Φ_B0 and (n⁻¹–1) vesus q/2kT and Φ_B0 versus n plots were drawn to get an evidence of Gaussian distribution (GD) of the barrier heights. These plots, too, show two linear regions corresponding to low (80–160 K) and high (200–340 K) temperature ranges (LTR and HTR), respectively. Mean value of barrier height (_B0) and standard deviation (σ_s) were extracted from the intercept and slope of Φ_B0 versus q/2kT plots for two linear regions as 0.382 eV, 0.0060 V for LTR and 0.850 eV, 0.135 V for HTR at low biases and 0.364 eV, 0.0059 V for LTR and 0.806 eV, 0.132 V for HTR at high biases, respectively. _B0 and Richardson constant (A*) values were also obtained from the intercept and slope of the modified Richardson (Ln(I_o/T²)−(q²σ_s²/2k²T²) versus q/kT) plots as 131.81 Acm⁻² K⁻², 0.381 eV for LTR and 129.35 Acm⁻² K⁻², 0. 854 eV for HTR at low biases and 148.01 Acm⁻² K⁻², 0.377 eV for LTR and 143.77 Acm⁻² K⁻², 0.812 eV for HTR at high biases, respectively. In conclusion, CTM in the structure can be successfully explained in terms of thermionic emission theory with the double GD of barrier heights.

Keywords:

• Au/Ca₃Co₄Ga_0.001O_x/n-Si/Au structures
• temperature and voltage dependent
• modified richardson plot
• double Gaussian distribution