Evaluating the abrasive wear of Zn1−xMnxO heteroepitaxial layers using a nanoscratch technique

In this study, we used nanoscratch techniques under a ramping load to evaluate the abrasive wear of Zn1−xMnxO epilayers (0 ⩽ x ⩽ 0.16) grown through molecular beam epitaxy (MBE) on sapphire substrates. We analyzed the surface roughness and damage using atomic force microscopy (AFM) and nanoindenter techniques. The scratched surfaces of the Zn1−xMnxO epilayers were significantly different for the various Mn compositions. AFM imaging of the Zn1−xMnxO films revealed that pileup phenomena were important on both sides of each scratch. During the scratching process, we found that cracking dominated in the case of Zn1−xMnxO films while ploughing; also we observed lower values of the coefficient of friction and shallower penetration depths for the films upon increasing the Mn content (x) from 0 to 0.16, suggesting that higher Mn contents provided the Zn1−xMnxO epilayers with higher shear resistances, enhanced by the presence of MnO bonds.