Confocal Raman Spectroscopy: Pillars (d=100 μm , h=20 μm) were fabricated. Raman spectra were collected with a confocal Raman spectrometer (Renishaw InVia Reflex) in backscattering configuration equipped with a 532 nm laser and a 50× long working distance objective (Olympus, NA = 0.5). A calibration with a silicon wafer at 520.6 cm -1 was performed prior to each measurement. Each spectrum was recorded with 75 s of bleaching time, 2 s of integration time, 20 accumulations, and laser power of 100%. For all samples, n = 3 measurements were performed at random points, with 3 repeats per scan speed and laser power parameter, with a focus point centered 1 μm below the surface to exclude an influence of surface inhomogeneities.