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

ÇİÇEK O., ALTINDAL Ş. , Azizian-Kalandaragh Y.

IEEE SENSORS JOURNAL, cilt.20, ss.14081-14089, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 20 Konu: 23
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1109/jsen.2020.3009108
  • Sayfa Sayıları: ss.14081-14089


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 (phi(Bo)-phi(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 phi(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 discrepancies and 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 Nss 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 mu A as against much greater values of -8.2 mV/K (LTs)/-7.9mV/K (HTs) for I = 10 mu A.