Strain-related optical properties of ZnO crystals due to nanoindentation on various surface orientations

Abstract

Nanoindentations were performed on various crystallographic orientations of single crystal ZnO using a cono-spherical diamond tip with a radius of curvature of 260 nm. The crystal orientations were the (112¯0) a-plane, (101¯0) m-plane, and (0001) c-plane (Zn-face). The optical properties associated with nanoindentation have been investigated by cathodoluminescence. The load-displacement curves show that the c-plane is the most resistive to deformation, followed by the m-plane, and the a-plane. A large number of non-radiative defects are created directly below the indentation, regardless of the crystal orientation. Nanoindentation on the a- and m-plane crystals activates slip along the (0001) basal planes, creating a band of non-radiative defects as well as tensile strain along the basal planes. Compressive strain is observed perpendicularly to the basal planes due to an absence of easy-glide mechanisms in these directions. The nanoindentation on the c-plane crystal results in regions under tensile strain extending away from the indentation along the six-fold a-directions.

First-principles theoretical study on band of strained wurtzite Nb-doped ZnO

“…So, research of ZnO has become a hot topic in the international optoelectronic fields over the recent years [1][2][3][4][5] .…”

Crystal Indentation Hardness

“…Tribological concern has been with chemomechanical aspects of sapphire crystal, polycrystal ZnO coating and other ceramic material hardness properties [26]. In addition, there are interesting optical (cathodoluminescence) properties associated with dislocation zones at nanoindentations in ZnO crystals [27].…”

“…In addition, there are interesting optical (cathodoluminescence) properties associated with dislocation zones at nanoindentations in ZnO crystals [27].…”

Nano-scaled diffusional or dislocation creep analysis of single-crystal ZnO

“…1,2 As being usually fabricated into low-dimensional piezoelectric devices, it is necessary to measure the mechanical properties of singlecrystal ZnO by contact-induced deformation through nanoindentation. [3][4][5][6][7][8][9][10][11][12][13] In this regard, the timedependent (so called creep) behavior is especially important in order to assess its mechanical reliability during devices being on service under long-term stress conditions. However, only few researches have been performed on the topic of nanoscale creep behavior of single-crystal ZnO with vertically (0001) orientation.…”