The probe of current conduction mechanisms, interface states, and the forward bias intersection point of the al/Al2O3/Ge/p-Si heterostructures depending on temperature

Abstract

The current conduction mechanisms (CCMs), temperature-sensitivities (S), energy-dependent interface traps (Nss), and origin of the intersection points in the forward bias (IF−VF) plots of the Al/Al2O3/Ge/p-Si heterostructure were investigated in wide temperature range of 90–420 K. Firstly, main electrical parameters, including reverse-saturation current (Io), ideality factor (n), zero-bias barrier-height (ΦBo), and series-resistance (Rs) values, were extracted for each temperature. The lnIF-VF curves illustrate two distinct linear regimes at low and intermediate bias voltages. Despite the observed decline in n values as temperature rises, the corresponding ΦBo values exhibit an upward trend. The conventional Richardson plots deviated from linearity at low temperatures, and the Richardson-constants (A*) value obtained from its linear part is quite lower than its theoretical value. Hence, ΦBo−q/2 kT, ΦBo−n, and n(kT)/q−(kT/q) correlations were plotted to seek indications of the Gaussian distribution (GD) of barrier heights (BHs) and tunneling mechanism. Temperate sensitivity (S = dV/dT) for 0.01, 0.10, 0.50, and 1 μA was found as 2.30, 2.33, 2.34, and 2.35 mV/K, which indicated that the fabricated Al/Al₂O₃/Ge/p-Si heterostructure is highly sensitive to temperature, rendering it suitable for use in temperature sensor applications. The observed crossing point at about 2.4V was explained by an increase in the apparent BH with temperature and the presence of Rs.