Fermi energy-level shift of p-type AgBiSe₂ single crystal featuring semiconductor-to-metal transition at cryogenics

Abstract

The ternary chalcogenide AgBiSe2(ABS) crystal was grown using the Bridgman Stockbarger technique followed by XRD and Raman shift analysis to verify the structural properties of the ABS crystal. The temperature (300 K- 4.2 K) dependent resistivity (ρ) elucidates semiconductor behavior up to 109 K, and suddenly ρ decreases with decreasing temperature, elucidates metallic behavior up to 19 K but soon after ρ increases with further decrease in temperature owing to the impurities in the crystal. The charge defects caused by atomic vacancies as well as anti-site defects are thermodynamically induced and they have the potential to shift the Fermi energy level. The two lucid transitions at 109 K and 19 K in ρ(T) demonstrate consequent changes as a semiconductor-to-metal transition. The MR graph substantially displays the resistivebehavior with respect to the magnetic field applied and portraits the ‘U’ shape at 300K to the ‘V’shape at 4.2 K, proclaiming a sluggish to active resistive transition with respect to the magnetic