Pressure Response of the UV-Photoluminescence of ZnO and MgZnO Nanocrystallites

ZnO and Mg$_{x}$Zn$_{1-x}$O are promising next-generation wide-bandgap semiconductors for high efficiency optical applications. Mg$_{x}$Zn$_{1-x}$O alloys enable the tuning of the photoluminescence\footnote{L. Bergman, et. al, Appl. Phys. Lett. \textbf{88}, 023103 (2006)} [PL] at the range of $\sim $ 3.0 -- 7.0 eV. Additionally, nanomaterial properties under high pressure are of significant importance to the field of devices operating under extreme conditions. Here, we present studies of the pressure response of the UV-PL of ZnO and Mg$_{0.1}$Zn$_{0.9}$O nanocrystallites of size $\sim $ 30 nm. We found that up to 6 GPa the pressure coefficients of ZnO and MgZnO are 23 and 27 meV/GPa, respectively. The pressure coefficient of the ZnO nanocrystallites is similar to that of the bulk ZnO. The higher value found for Mg$_{0.1}$Zn$_{0.9}$O is discussed in terms of the atomic numbers of the cation constituents. L. B. acknowledges NSF-CAREER-DMR-0238845, and DOE--DEFG02-04ER46142. M. M. and L. B. acknowledge the ACS PRF-40749AC10.