Taxonomy of high pressure vibration spectra of zincblende semiconductor alloys based on the percolation model.

Due to their simple structure (two bond species randomly arranged on a cubic lattice), the zincblende ABC 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 (homo) or alien (hetero) environments (1-bond → 2-mode 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 homo/hetero 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 CdZnTe 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.