Thermal stability of magnetron sputtering Ge-Ga-S films

Ge-Ga-S thin films were deposited by magnetron sputtering with mean coordination number (MCN) ranging from 2.46 to 2.94. The physical properties of the Ge-Ga-S films, including optical band gap, refractive index, and thickness, vary with the time of heat treatment. Based on the analysis of the topology model, it is concluded that the Ge-Ga-S thin films with components close to the stoichiometric ratio can form the most Ga-S bonds and Ga-S bonds, and the physical properties of the Ge_27.3Ga_6.3S_66.3 (MCN=2.62) film are the most stable. This is an important reference for thin film photonic devices.