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Article Citation - WoS: 10Citation - Scopus: 11Structural and Temperature-Tuned Bandgap Characteristics of Thermally Evaporated β-in2< Thin Films(Springer, 2021) Surucu, O.; Isik, M.; Terlemezoglu, M.; Gasanly, N. M.; Parlak, M.In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309 and 369 cm(-1) were observed in the Raman spectrum. Temperature-tuned bandgap energy characteristics of the In2S3 thin films were revealed from the investigation of transmittance spectra obtained at various temperatures between 10 and 300 K. The analyses of the transmittance spectra indicated that direct bandgap energy of the In2S3 thin films decreases from 2.40 eV (at 10 K) to 2.37 eV (at 300 K) with the increase of measurement temperature. The bandgap energy vs. temperature relation was investigated by means of Varshni optical model. The fitting of the experimental data under the light of theoretical expression revealed the absolute zero bandgap energy, the rate of change of bandgap energy and Debye temperature.Article Citation - WoS: 29Citation - Scopus: 29Frequency Effect on Electrical and Dielectric Characteristics of Hfo2-interlayered Si-Based Schottky Barrier Diode(Springer, 2020) Gullu, H. H.; Yildiz, D. E.; Surucu, O.; Parlak, M.This study reveals the electrical properties of In/HfO2/n-Si structure with atomic layer-deposited interfacial oxide layer, HfO2 thin film between In top metal contact and monocrystalline Si wafer substrate. From the dark current-voltage measurements, the diode structure showed good rectifying behavior and low saturation current of about two order of magnitude and 1.2 x 10(- 9) A, respectively. According to the conventional thermionic emission model, zero-bias barrier height and ideality factor were calculated from the forward bias current-voltage curve at room temperature under dark conditions as 0.79 eV and 4.22 eV, respectively. In order to get detailed information about density of interface states and series resistance of this structure, capacitance-voltage and conductance-voltage measurements in the frequency range of 10-1000 kHz were performed. As a result, a decreasing capacitance profile with increasing frequency was obtained. In addition, peak-like behavior in the capacitance profiles was observed and these were found to be the indication of density of states. Further analysis was performed on the evaluation of density of interface states values and these values were calculated by using two different methods: Hill-Coleman and high-low frequency capacitance. These profiles were also analyzed by eliminating the effect of series resistance values on the measured capacitance and conductance; then the values of corrected capacitance and conductance as a function of applied voltage were discussed. Based on these analyses on the capacitive characteristics of the diode, dielectric constant, dielectric loss, loss tangent, electrical conductivity, and the real and imaginary part of electric modulus were investigated for complete understanding on the diode characteristics.
