Model for bond-breaking mechanisms in amorphous arsenic chalcogenides leading to light-induced electron-spin resonance

A model is presented for the light-induced bond-breaking processes in arsenic chalcogenides which, based on theoretical calculations of coordination defects, accounts for the details of recent experimental light-induced electron-spin resonance experiments on amorphous ${\mathrm{As}}_{\mathit{x}}$ ${\mathrm{S}}_{1\mathrm{-}\mathit{x}}$ alloys. The presence of homopolar (wrong) bonds is essential in such compound materials for the optically induced creation of metastable paramagnetic dangling-bond defects, but the creation process does not involve the scission of such homopolar bonds themselves.