Diode Polarization and Resistive Switching in Metal/TlGaSe2 Semiconductor/Metal Devices

The Franz–Keldysh effect in the optical absorption spectrum of a TlGaSe2 layered semiconductor caused by charged native defects

“…Memristive (resistive-switching) memory effects have been recently observed by authors in nominally undoped bulk TlGaSe 2 samples [32,33]. Diode-type nonlinear currentvoltage characteristics in metal-TlGaSe 2 -metal structures have been revealed.…”

“…In these structures, the rectification direction depends only on the polarity of previously applied bias to the electrodes and is independent of the electrode materials. This phenomenon has been understood within the framework of electromigration of charged entities (native Se vacancies or Se ions) leading to the formation of a thin insulator layer near the biased TlGaSe 2 sample surface [32,33].…”

A Study of Thermoelectric Performance of TlGaSe2 Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

“…[ 1–4 ] In bulk form, is a p‐type semiconductor with optical bandgap in the visible spectral range (≈2.1 eV) at room temperature. [ 5–9 ] grows in the form of multilayers where layers are weakly interacting through van der Waals forces along the direction. Within the layers, every atom is strongly bonded with neighbor ones via ion‐covalent chemical bonding mechanism.…”

“…At room temperature the electronic transport mechanism in the direction parallel to the layers is directly related to the presence of localized states in the bandgap created by native structural defects. [ 7–19 ] The electrical conduction perpendicular to the layers is expected to be highly sensitive to inevitable structural defects such as: planar defects presented between the layers due to a slipping of successive layers, point defects, charged impurities, deep level traps, dislocations as well as to many other crystal lattice imperfections that are mainly attributed to the interlayer stacking faults. [ 20–22 ] Only at extremely high temperatures, due to the thermally activated free carriers from the valence band the intrinsic electrical conduction is determined by a band‐to‐band mechanism.…”

“…[ 5,7 ] These chalcogen vacancy defects severely affect the charge transport properties of and could be responsible for two nontrivial electronic features of this compound. [ 7,8,33,34 ] Thus, a sets of selenium vacancies should be localized in various atomic sites of unit cell due to compositional inhomogeneities forming during crystal synthesis or post‐growth treatment. It is possible that, the chalcogen vacancies are responsible for normally always p‐type conduction behavior of this material.…”