Browsing by Author "Azizian-Kalandaragh Y."

Now showing 1 - 2 of 2

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
(2020-12-01) Cicek O.; Altindal S.; Azizian-Kalandaragh Y.
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 ( $\phi _{\textit {Bo}}$ - $\phi _{\textit {ap}}$ ) increases while the ideality factor ( ${n}$ ), series and shunt resistances ( ${R} _{s}$ , ${R} _{\textit {sh}}$ ), rectifying rate (at ±2V) and surface states ( ${N} _{\textit {ss}}$ ) decrease with increasing temperature. The $\phi _{\textit {Bo}}$ , ${n}$ and ${R} _{s}$ values are also extracted from Cheung's functions and, then compared with those obtained TE theory. The conventional Richardson plot ( $\ell {n}$ ( ${I} _{o}$ /T 2)-q/kT) displays the deviation from the linearity at low-temperatures ( $T\le140$ K). Besides, the experimental value of Richardson constant ( ${A} ^{\ast }$ ) 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 ${N} _{\textit {ss}}$ 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 ${I} =0.1\,\,\mu \text{A}$ as against much greater values of -8.2 mV/K (LTs)/-7.9mV/K (HTs) for ${I} = 10\,\,\mu \text{A}$.
Frequency Response of C–V and G/ω-V Characteristics of Au/(Nanographite-doped PVP)/n-Si Structures
(2021-01-01) Akbaş A.M.; Çiçek O.; Altındal Ş.; Azizian-Kalandaragh Y.
This paper reports that frequency response on profile of C–V–ƒ and G/ω–V–ƒ characteristics of spin-coated nanographite (NG)-doped polyvinylpyrrolidone (PVP)/n-Si structures in a wide frequency (1 kHz–5 MHz) and voltage (± 3 V) ranges at room temperature. Hereby, the basic parameters of the structure such as diffusion potential (VD), doping donor density (ND), Fermi energy level (EF), maximum electric field (Em), depletion layer thickness (Wd), and barrier height (ΦB) are derived by using the intercept and slope of C−2–V–ƒ plot for each frequency. Additionally, the energy density distribution of surface states (Nss) and their relaxation time values (τ) are also attained from the conduction method and their values are found as 4.999 × 1012 eV−1 cm−2 and 2.92 µs at 0.452 eV, and 3.857 × 1012 eV−1 cm−2 and 164 µs at 0.625 eV, respectively. The lower Nss values are the consequence of passivation effect of the used nanographite (NG)-PVP polymer interlayer. As a result, the polymer interlayer based nanographite (NG)-PVP is candidate instead of the widely used oxide/insulator layer for the purpose of decreasing the surface states or dislocations.