A Highly Sensitive Temperature Sensor Based on Au/Graphene-PVP/n-Si Type Schottky Diodes and the Possible Conduction Mechanisms in the Wide Range Temperatures

We report that the sensitive temperature response and possible Conduction Mechanisms (CMs) of Au/graphene-PVP/ n-Si type Schottky diodes (SDs) are investigated using the standard Thermionic Emission (TE) theory at low temperatures (LTs) and high temperatures (HTs). The obtained results indicate that the zero-apparent barrier height (φ
_Bo
-φ
_ap
) increases while the ideality factor (n), series and shunt resistances (R
_s
, R
_sh
), rectifying rate (at ±2V) and surface states (N
_ss
) decrease with increasing temperature. The φ
_Bo
, n and R
_s
values are also extracted from Cheung's functions and, then compared with those obtained TE theory. The conventional Richardson plot (ℓn(I
_o
/T
²
)-q/kT) displays the deviation from the linearity at low-temperatures (T ≤ 140 K). Besides, the experimental value of Richardson constant (A*) deduced from the intercept of plot was found to be several orders lower than the theoretical value. The discrepanciesand higher values for the parameter of n are important evidences for the deviation from TE theory. This is mainly attributed to the spatial inhomogeneities of the barrier height and potential fluctuations at the interface including low/high barrier areas. Hence the CMs across diode preferentially flows through these lower barriers/patches at the regions of LTs. The decrement in the N
_ss
with the enhancement in the temperature is in relation to the molecular restructuring-reordering under temperature and voltage effects. The SDs fabricated with graphene-PVP interlayer exhibit a higher sensitivity (S) rather than many silicon/SOI-based structures. Numerically, the S values are found to be in a range of 1.3 mV/K (LTs)/-1.93mV/K (HTs) in case of I = 0.1 μA as against much greater values of -8.2 mV/K (LTs)/-7.9mV/K (HTs) for I = 10 μA.