Exploring dielectric and AC conduction characteristics in elemental selenium glass modified with silver halides

Area of Science:

• Materials Science
• Solid State Physics
• Condensed Matter Physics

Background:

• Elemental selenium exhibits interesting dielectric properties.
• Doping with silver halides can modify these properties.
• Understanding charge transport mechanisms is crucial for material applications.

Purpose of the Study:

• To investigate the effect of silver halide (AgI, AgBr, AgCl) doping on selenium's dielectric dispersion and AC conduction.
• To determine the dominant charge transport mechanisms in doped selenium.
• To compare the dielectric performance of different silver halide dopants.

Main Methods:

• Synthesis of selenium-silver halide alloys (Se95(AgX)5, where X = I, Br, Cl).
• Measurement of dielectric constant (ε'), dielectric loss (ε''), and AC conductivity (σac).
• Analysis using relevant transport models like Correlated Barrier Hopping (CBH) and Non-Overlapping Small Polaron Tunneling (NSPT).

Main Results:

• Doping with silver halides causes noticeable changes in dielectric properties and AC conductivity.
• Pure selenium and Se95(AgI)5 follow the CBH model (polaron hopping).
• Se95(AgBr)5 predominantly shows NSPT mechanism.
• Se95(AgCl)5 exhibits both NSPT and CBH mechanisms depending on temperature.
• Silver iodide doping provides the best optimization of dielectric constant and loss.

Conclusions:

• Silver halide doping effectively tunes the dielectric and AC conduction properties of selenium.
• The charge transport mechanism is dependent on the specific silver halide dopant and temperature.
• Silver iodide-doped selenium demonstrates superior dielectric performance compared to other silver halide dopants and some existing chalcogenide glasses.