Mechanical Property Evaluation of GaAs Crystal for Solar Cells

The mechanical properties of Si-doped (111) GaAs crystal for solar cells are investigated by means of a microindentation technique. Vickers' microhardness H_v exhibits a nonlinear relationship with the applied load. In the range of 0.1–1 kg, H_v is decreased from 5.59 GPa to 5.03 GPa. Such a phenomenon is explained on the basis of indenter penetration. The H_v value can effectively be presumed by Kick's law, and Meyer's index n is calculated to be 1.90. For the fracture toughness K_c of the GaAs crystal, it also displays nonlinear behavior related to the applied load, which is caused by energy dissipation during the development process of cracks on the wafer.