Constant di/dz Scanning Tunneling Microscopy: Atomic Precision Imaging and Hydrogen Depassivation Lithography on a Si(100) - 2 x 1 : H Surface

TL;DR

This paper presents a new STM control mode using di/dz feedback with high-frequency modulation, enabling atomic precision imaging and hydrogen depassivation lithography on Si(100)-2x1:H surfaces.

Contribution

It introduces a novel di/dz feedback technique for STM that improves sensitivity and resolution in surface imaging and lithography.

Findings

Effective high-resolution imaging demonstrated

Enhanced surface sensitivity over conventional methods

Successful lithography on Si(100)-2x1:H surfaces

Abstract

We introduce a novel control mode for Scanning Tunneling Microscopy (STM) that leverages di/dz feedback. By superimposing a high-frequency sinusoidal modulation on the control signal, we extract the amplitude of the resulting tunneling current to obtain a di/dz measurement as the tip is scanned over the surface. A feedback control loop is then closed to maintain a constant di/dz, enhancing the sensitivity of the tip to subtle surface variations throughout a scan. This approach offers distinct advantages over conventional constant-current imaging. We demonstrate the effectiveness of this technique through high-resolution imaging and lithographic experiments on several Si(100)-2x1:H surfaces. Our findings, validated across multiple STM systems and imaging conditions, pave the way for a new paradigm in STM control, imaging, and lithography.