Electronic properties and phase transitions in low-dimensional semiconductors

Abstract

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, nonlinear effects in their I–V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor–metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. The electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.

Электропроводность и диэлектрические характеристики твердых растворов Tl(GaS-=SUB=-2-=/SUB=-)-=SUB=-1-x-=/SUB=-(InSe-=SUB=-2-=/SUB=-)-=SUB=-x-=/SUB=-

“…В обзоре [7] приведен анализ результатов исследова-ний физических свойств соединений группы TlB III C VI 2 . Показано, что, несмотря на многочисленные исследова-ния этих соединений, многие их физические характери-стики не совпадают, в частности, значения температур ФП, приводимые разными авторами для одних и тех же кристаллов, сильно различаются.…”

Electron-Deformational Phase Transitions in a TlGaSe2Layered Crystal

“…Recently, a ternary layered TlGaSe 2 crystal has attracted considerable interest due to its ferroelectric and semiconducting properties as well as sequences of the structural phase transition [1,2]. In this crystal transitions from the high temperature paraphase to the incommensurate phase at T i = 118 K, and then to the commensurate ferroelectric phase at T c = 108 K, as well as the existence of additional metastable phases [2] have been identified.…”

Analysis of Thermoluminescence Glow Peaks in β-Irradiated TlGaSeS Crystals

“…They are promising for various technological applications, especially for optoelectronic device applications due to its high photosensitivity and components in the visible range of spectra and high birefringence in conjunction with a wide transparency range of 0.5-14.0 µm [2][3][4]. In the crystal structure of TlGaSeS, Tl and Se(S) atoms are bonded with an interlayer type whereas bonding between Ga and Se(S) atoms is intralayer type.…”