Taxonomy of high-pressure vibration spectra of zincblende semiconductor alloys – The percolation model applied to Cd(1-x)Zn(x)Te

Abstract

Due to their simple structure (two bond species randomly arranged on a cubic lattice), the zincblende A(1-x)B(x)C semiconductor alloys (zb-SCA) set a benchmark to explore how physical properties are impacted by disorder. A longstanding controversy was whether the lattice dynamics (phonons), governed by the bond force constant, i.e., a local physical property, is “blind” to the alloy disorder or actually “sees” it. Over the past two decades, we introduced the percolation model (PM) that distinguishes between like bonds depending on whether they vibrate in “same” or “alien” environments (1-bond→2-phonon scheme). The PM seems to apply universally among zb-SCA, and hence would solve the controversy in favor of the second scenario. Here our aim is to take one step forward and complete in the main lines a PM-based taxonomy of high-pressure vibration spectra of zb-SCA. This might clarify how a disordered atomic alloy, seen by each bond species in terms of a “same/alien” composite (i.e., at the unusual mesoscopic scale) from the angle of the PM, behaves when the lattice shrinks under hydrostatic pressure. We focus on Cd(1-x)Zn(x)Te as the last sensitive pending case. This tidying-up exercise is attractive at the fundamental level and useful for projecting phonon-based devices involving zb-SCA.