Ac conductivity and dielectric properties of TlIn_0.975Y_0.025S₂ single crystal

Abstract

The frequency dependence of the electrical conductivity, dielectric properties, and dielectric loss of TlIn0.975Y0.025S2 single crystal was studied in the temperature range 303–473 K over the frequency range 102–105 Hz. A characteristic frequency, ωp, was found involved in the conduction mechanism, above which the electrical conductivity increased sharply. This observed variation was explained according to Summerfield theory for hopping conductivity which predicted a scaling law for the low‐frequency ac conductivity: σ(ω) = σ(0) [1 + (ω/ωp)β]. At higher frequency (≥4 kHz) the ac conductivity increased sharply with frequency according to the power law σac ≈ Aωs. The analysis of the ac conductivity at higher frequency showed that the correlated barrier hopping model is the most appropriate mechanism. Also, the loss tangent, tanδ, was predicted to decrease with increasing frequency. Capacitance was found to decrease with increasing frequency and decreasing temperature. The capacitance reached a minimum value, Cmin, at higher frequencies. Finally the maximum barrier height, WM, the hopping energy, ωH, the relaxation time, τ, and the density of states, N(Ef), for TlIn0.975Y0.025S2 single crystals were determined. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural and electrical properties of thermally evaporated cobalt phthalocyanine (CoPc) thin films

“…The ac conductivity and some dielectric properties were measured over 100 Hz to 1 MHz frequency range and 298 to 423 K temperature range. A programmable automatic RLC bridge was used to measure the impedance Z, the capacitance C, similar to that described in [21].…”

“…The real part of dielectric constant, ε 1 , [see the inset of Fig. 7], decreases from 1.622 to 1.76 as the frequency increases from 100 Hz to 1 MHz, while it increases slightly from 0.85 to 0.898 as the temperature increases from 298 to 407 K. This behavior can be attributed to the effect of charge redistribution by mean carrier hopping on defects [21,[60][61][62].…”

Electronic and Photovoltaic Properties of p-Si/PCBM:MEH-PPV Organic-Inorganic Hybrid Photodiode

“…Organic photovoltaic devices are promising candidates for renewable sources of electrical energy because of ease in fabrication and low production cost as well as light weight and flexibility [11][12][13][14]. Photodiodes based on polythiophene and its derivates organic semiconductors and different organic-inorganic heterojunctions such as pyronine-B/Si, β-carotene/Si, chitin/n-Si and poly[2-methoxy, 5-(2 -ethyl-hexyloxy)--1,4-phenylenevinylene] (MEH-PPV)/p-Si, 4-tricyanovinyl-N,N-diethylaniline/p-Si, Al/p-Si/copper phthalocyanine, chitosan/n-Si, organic/inorganic Schottky, FSS/n-Si, NiPc/p-Si, Zn(Phen)q/p-Si and ddq/p-Si have been fabricated and their electronic properties have been investigated [15][16][17][18][19][20][21][22][23][24]. The prospect of being able to generate electricity from sunlight has fuelled intensive research in inorganic and more recently in organic photovoltaics [25].…”