Scratch Characteristics of ZnMgO Epilayers

Abstract

Zn0.75Mg0.25O films were grown via metal organic vapor phase epitaxy on an M-plane sapphire substrate. We used nanoscratch tests to study the abrasive plow of the films; comparable cases of critical pileup were obtained on both sides of each scratch when the ramped load increased from 0 to 250 mu N. The film showed a crack in the bulge edge between the groove at ramped loads of 1000 mu N as well as full plastic deformation. The values of mu were 0.14, 0.33, 0.43, and 0.48 for the ramped loads of 250 mu N and 0.22, 0.26, 0.28, and 0.33 for the ramped load of 1000 mu N. We found that cracking dominated in the case of Zn0.75Mg0.25O films during plowing. Lower values of the coefficient of friction and shallower penetration depths were observed at RT, while higher values were observed in the annealed samples. It is suggested that higher growth temperatures induce lower bonding forces and reduce the shear resistances of Zn-0.75Mg0.25O films.