Jel 2100f

Ag-coated AuNRs with two different shell thickness were purchased from NanoSeedz (Hong Kong, China). Structural characterization of Ag@AuNRs with different shell thickness was performed by using transmission emission microscopy (TEM, JEL-2100F, JEOL) to ensure their shapes and sizes. Furthermore, their LSPR absorption spectra in water were measured under a Varian Cary 100 UV-Vis spectroscope (Agilent, USA).

The GaN wafer bow was measured by a digital micrometer (Mitutoyo ID-CX series with the comparator stands (BS series)). The sign of a wafer bow determines the shape of the mirror GaN layer, i.e., (+) bow for convex shape and (−) bow for concave shape. To estimate the wafer bow, first, the height of the wafer center was measured by putting the convex shape wafer on a reference table. Then, the wafer was flipped 180° and loaded on a reference table; afterward, the wafer center thickness was measured. The difference between the height of the convex shape wafer and the center wafer thickness flipped 180° indicated the wafer bow. In addition, the subsurface damaged layer (SSD) of the Ga-face mirror layer after polishing and the morphology of the CMP abrasives were observed by cross-sectional (x-) transmission electron microscopy (TEM) (JEOL JEL-2100F) at an accelerating voltage of 200 keV. The remaining threading dislocations and subsurface-damage-induced scratches were observed by scanning electron microscopy (SEM) (HITACHI S-4300) with cathodoluminescence (CL) (GATAN MONO CL3+). The images of the remaining scratches and surface roughness were estimated by atomic force microscopy (AFM) (Park Systems XE7).

We used transmission electron microscope (TEM, JEL-2100F, JEOL, Japan) and scanning electron microscope (SEM, JSM-6500, JEOL, Japan) to characterize the AuNRs@mSiO₂. The TEM images were analyzed based on a custom MATLAB script previously reported with some subroutine implemented in the image processing toolbox of MATLAB. Furthermore, a Varian Carry 300 UV-vis spectrometer (Agilent Technologies) was used to characterize the ensemble extinction spectrum of the AuNRs@mSiO₂.