Fig. 1.

Surface geometry of hydrogen-passivated Si(100)-2×1. a (V = 1.4 V, I = 50 pA, T = 4.5 K, 2 × 3 nm²) Scanning tunneling microscope (STM) image of hydrogen atoms bonded to the Si(100)-2×1 surface. The distance between identical sites along and across a dimer row are shown in yellow (solid). The surface geometry allows for the creation of single atom bits at ultra-high densities. The area of one bit (including spaces between atoms), 0.590 nm², is outlined in yellow (dashed), and is defined as a binary zero. The hydrogen atom denoted with a dot (green) is removed with an STM tip to create a dangling bond, changing the bit to a binary one. b 2D-Fourier transform (power spectrum) of a, where the three dominant spatial frequencies have been isolated. c–e Filtered STM images of a, for each dominant frequency (peak) shown in b, c bottom peak (blue), d top peak (yellow), e middle peak (red). f The resulting image from the sum of frequencies shown in c–e, reconstructing the essential features of the STM image shown in a, allowing for the position of each surface hydrogen atom to be determined. Scale bar, 1 nm