Fig. 1 Schematic of nanodisk arrays on an ultrathin c-Si wafer. c-Si nanodisk arrays are placed on the ultrathin c-Si wafers in two dimensional hexagonal arrays.

Fig. 2 (a) Reflectance contour map from c-Si bulk wafers with the nanodisk arrays of various periods and heights. The dashed line denotes a contour line of 10% reflectance. (b) Reflectance as a function of wavelength from c-Si bulk wafers with the nanodisk arrays of 100 nm height and three different periods (300 nm, 500 nm, 800 nm). For the sake of comparison, the reflectance from planar c-Si with ARC was also plot together. (c) Reflectance as a function of wavelength from c-Si bulk wafers with the nanodisk arrays of 500 nm period and four different heights (100 nm, 300 nm, 500 nm, 900 nm).

Fig. 3 (a) Reflectance contour map from c-Si bulk wafers with the antireflective coated nanodisk arrays. Periods and heights are varied. The dashed line denotes a contour line of 4% reflectance. (b) Reflectance as a function of wavelength from c-Si bulk wafers with the antireflective coated nanodisk arrays of 100 nm height and three different periods (300 nm, 500 nm, 800 nm). (c) Reflectance as a function of wavelength from c-Si bulk wafers with the antireflective coated nanodisk arrays of 500 nm period and four different heights (100 nm, 300 nm, 500 nm, 900 nm).

Fig. 4 (a) Fractional high order diffracted transmittance as a function of wavelength by varying the periods of the nanodisk arrays. (b) Photocurrents generated from the high order diffracted transmission in the wavelength range of 700 nm ~1100 nm as a function of the periods of the nanodisk arrays.

Fig. 5 (a) The maximum photocurrent generated in 2 micron thickness c-Si wafers as a function of nanodisk height and period. (b) Photocurrents generated from solar radiation in the short wavelength region (350 nm ~700 nm) and the long wavelength region (700 nm ~1100 nm). Total photocurrent (J_ph,total), which is the sum of J_ph1 and J_ph2, is also shown. (c) Absorption spectra of 2 micron thickness c-Si wafers with nanodisk texturing as a function of wavelength for various periods (dotted lines). The solid lines are smoothened data by adjacent averaging, which are displayed only for the eye guide.

Fig. 6 Contour map of photocurrents from 2 μm thickness c-Si wafers with varying filling factor and height.

Fig. 7 Surface area enlargements with nanodisk texturing for various periods and heights of the nanodisks. The numbers with the dashed line indicate the surface area enlargement contour lines corresponding to 1.5 and 2.0, respectively.

Fig. 8 (a) Simulated photocurrents generated in 2 μm thickness c-Si wafers with various texturing: A. planar with ARC, B. single side texturing with the nanodisk arrays of a 800 nm period, double side texturing with the nanodisk array periods of C. 800 nm, D. 1600 nm, and E. 2400 nm at the back side while the period of the front surface nanodisk arrays was maintained at 800 nm. The red dashed line indicates the maximum photocurrent in the Lambertian absorption limit. (b) Absorption spectra of 2 μm thickness c-Si wafers with single side or double side texturing of the nanodisk arrays. The absorption spectrum of planar c-Si with ARC is also shown for comparison. The blue and red solid lines are smoothened data for the eye guide. (c) Photocurrent density of c-Si wafers with texturing or without texturing and ARC for various c-Si wafer thickness. The Lambertian absorption limit is shown together. The cross-sectional images of c-Si wafers with single side or double side texturing are illustrated in the top figure. The nanodisk arrays are coated with orange-colored ARC. The yellow colored layer is an optical spacer of SiO₂. The gray layers denote the ideal reflector (PEC).