Determination of temperature dependent electrical and optical parameters of metal/organic/inorganic semiconductor structures

In this study (100) orientation, 500 μm thickness, at the room temperature having 1-10 Ω.cm resistivity n-type Si wafer at the room temperature with another (100) orientation, 270 μm thickness and p-type Si wafer having 1-10 Ω.cm resistivity at the room temperature were used. After waiting a short period of time for evaporating, the solution that belongs to the organic compound of 9,10-Dihydrobenzo[a]pyrene-7(8H)-one (9,10-H2BaP) on the bright surface of n-Si and p-Si semiconductors that was made ohmic contact, an organic thin film layer was generated on these surfaces. To able to obtain Schottky contacts Ag metal was evaporated thermally about under 2 10-6 Torr on the sides that were organic thin film coated of each two samples were evaporated with 1.5 mm diameter circular dots. Thus Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al Schottky diodes were obtained. Optical band gap of 9,10-H2BaP organic thin film was obtained using absorbance spectrum of 9,10-Dihydrobenzo[a]pyrene-7(8H)-one (9,10-H2BaP) organic thin film on the quartz surface. In addition, I-V measurements of Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al diodes measured under light which had intensity of 40-100 mW/cm2 and these structures were investigated sensitivities against light and photoelectrical properties. It is observed for both diodes that the reverse bias current of the diodes with increasing the light intensity, increases also. Thus the structures determined that the photodiode property and can be used in optoelectronic applications. Obtained Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al diodes were taken I-V, C-V and G/ω-V measurements with 40 K steps from 80 K to 280 K and with 20 K steps from 280 K to 360 K. Barrier heights and ideality factors were found from I-V graphics. It was seen that the obtained barrier height was increased with the increasing temperature, but the ideality factor was decreased. This situation was attributed to the lateral inhomogeneity of the barrier. Also Richardson plots were drawn with the help of I-V measurements for high and low temperature regions. From these plots, the mean barrier height and Richardson constant values were found. Furthermore, the mean barrier height and standard deviation values were obtained from barrier height-temperature graphics. The C-V and G/ω-V measurements of Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al diodes were taken at 1 MHz in the 80-360 K temperature range and the graphics of these measurements were drawn. For both diodes diffusion potential, barrier height and Fermi energy level values were obtained with the help of C-V graphics. It was seen that the capacitance and conductance increased with increasing temperature. Also C-V and G/ω-V characteristics of Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al diodes were examined at room temperature and in a wide frequency range. It was seen that the capacitance and conductance values were decreased with the increasing frequency. This situation was explained as dependent on increasing frequency, that interface states (Nss) cannot follow the ac signal. Dielectric properties; dielectric constant ( ), dielectric loss ( ), loss tangent ( ), electric modulus ( and ) and ac electrical conductivity values of structures were obtained from the measurements of C-V-f and G/ω-V-f that depend on frequency and C-V-T and G/ω-V-T that depend on temperature of Ag/9,10-H2BaP/n-Si/Au-Sb and Ag/9,10-H2BaP/p-Si/Al diodes. Changes of the obtained these parameters were examined against temperature and frequency. Experimental results have showed that the dielectric parameters were quite strongly temperature and frequency dependent.