Effects of an in vacancy on local distortion of fast phase transition in Bi-doped In₃SbTe₂

Indium vacancies in Bi-doped In3SbTe2 (BIST) cause local distortion or and faster phase transition of BIST with good stability. The formation energy of the In vacancy in the BIST is relatively lower compared to that in IST due to triple negative charge state of the In vacancy (V³⁻ _In) and higher concentration of the V³⁻ _In in BIST. The band gap of BIST is substantially reduced with increasing concentrations of the V³⁻ _In and the hole carriers, which results in a higher electrical conductivity. The phase-change memory (PRAM) device fabricated with the BIST shows very fast, stable switching characteristics at lower voltages.