Specific features of conductivity of γ-irradiated TlGaTe2 crystals with nanochain structure

Prospective Application of A3B3C62 Type Semiconductors for Developing Nano-size Electronic Devices

“…Hanias and Anagnostopoulos [12], studying the current-voltage (I-V) characteristics of a TlGaTe2 crystal, detected the effect of negative differential resistance and voltage oscillations in the region of negative differential resistance. Our investigations [4,5,[13][14][15][16][17][18][19][20] revealed that TlGaTe2 chain crystals are subjected to phase transition in superion state, and demonstrated giant dielectric relaxation, substantial increase of dielectric permeability, and negative differential conductivity. All of these effects are connected with the transition of systems in superion state, when there is softening of Tl 1+ sublattice (Figure 1), while prolonged along tetragonal axis c of crystal Ga 3+ -Te 2-2 chains are the core of system.…”

“…Due to weak THz transmission in the absorption bands, the typical means of determining the index of refraction and coefficient of absorption are not valid. Thus, we used a method described in [4], combining measurements in both: transmission and reflection. The basic idea is to derive a rough estimation of the refractive index from reflection data, while both refractive index and absorption coefficient are also calculated from transmission data.…”

“…In [4] the conductivity in the ohmic region over the allowed band in the direction of chains and perpendicularly to them is accomplished by thermally excited charge carriers in TlGaTe2 single crystals as temperature is lowered in the range 300-90 K. As temperature is lowered, the charge transport is accomplished by hops of charge carriers over localized states near the Fermi level; these hops are more energetically favourable although they are more distant spatially. As temperature is lowered further, the conventional hopping conductivity is observed, in which case the mean length of a hop for charge carriers amounts to a value on the order of the mean distance between impurities and does not change as temperature varies.…”

“…Superionic conductivity was observed at temperatures above 300 K. We also studied the temperature dependences of σ(T) and current-voltage characteristics subjected to various doses of γ-radiation in both geometries of the experiment, along nanochains parallel to the tetragonal axis of the crystal and perpendicular to these nanochains. The results show that the physical parameters of nanochains can be controlled by the choice of doses of γ-irradiation [4,5]. In our opinion, the possibility of re-ordering of nanochains in these crystals under the γ-ray irradiation opens new prospects in the development of nano-size varistors, electrochemical devices purposed for the transformation and accumulation of energy, charges and information.…”

Superionic Conductivity in One-Dimensional Nanofibrous TlGaTe2 Crystals

“…1) gives the activation energy ÁE a ¼ 0:21 eV for TlGaTe 2 , in agreement with published values. 4,5) The observed sharp growth of the TlGaTe 2 conductivity of crystals results from the variation with temperature of the high-mobility ion density in the crystal. This variation is mainly caused by the diffusion of the Tl þ ions towards vacancies in the Tl sublattice.…”