Introduction

Hello, this project is aimed at building an atomic-level scanning tunneling microscope through DIY.

As of June 2022, this project has successfully measured the tunneling distance-current curve, the scanning tunneling spectrum curve (STS) of pyrolytic graphite (HOPG), and size-free qualitative imaging of the sample.

Introduction to the structure of open source files (attachments)

*Due to time constraints, detailed documentation will be completed later.

• Archive
  This directory contains open source materials for the first generation microscope. For details, please see its readme (for file size restrictions, please go to Github )
• The 3DModel
  directory includes shell design files and STEP files required for CNC processing.
• Software
  This directory includes microcontroller programs (completed using Arduino and PlatformIO ), Python programs for controlling the microcontroller (communicating with the microcontroller through the serial port, and the interface design is based on QT), and Python programs for converting scanned images.
• Document
  This directory includes papers and data manuals referenced during the development process. (For file size restrictions, please go to Github )

Circuit part

• Click "Open Editor" in the upper right corner.

Achievements

Tunneling distance-current curve

Scanning tunneling spectral curve of pyrolytic graphite (HOPG)

Size-free qualitative imaging of pyrolytic graphite (HOPG) samples

contact me

If you also want to make an STM microscope, or have any suggestions for me, you can submit an Issue on this page.

Development records

• 2021/11

  unstable tunneling

• 2022/1/11

  Open source page submission

• 2022/1/18

  A <tennis ball> is installed under the shock-absorbing table, and the shock-absorbing effect is outstanding.

• 2022/2/05

  1) The analog part of the system is powered by a 9V battery, and the digital part continues to use switching power supply.
  2) ADP5070 doesn’t work, grandma’s fault! Why.
  3) In "Construction of a scanning tunneling microscope for imaging of carbon nanotubes" P35, it was found that the tunneling current should be between 100pA and 10nA. According to the multiple of the existing op amp, the signal should be focused on within 1V. It seemed that I had made a mistake before.
  4) The open-loop voltage gain of OPA627 is 120dB, and the input bias current is 1pA. Logically speaking, it should be feasible to use a 100MΩ feedback resistor?

• 2022/2/16

  The input and output characteristics of the operational amplifier were tested, proving that the pre-stage tunnel current amplification circuit is feasible.

• 2022/3/14

  1) The new structure of CNC processing is completed
  2) Abandon LVGL and display screen as the control system

• 2022/3/21

  New structural systems, circuits, and control systems were used to conduct tunneling current approach tests:
  1) The tunneling current is initially stable and can be maintained for more than ten seconds.
  2) Through sampling and testing at eight points, the tunneling current-piezoelectric ceramic deformation curve was found to basically conform to exponential characteristics.
  3) Confirm that a very complicated damping system is not required.
  4) It is basically confirmed that the output jumping phenomenon that occurred before is a thermal expansion mismatch.

• 2022/4/12

  1) After adjusting the thermal isolation of the stepper motor in the approach mechanical structure, the tunneling current has been very stable and can be maintained for at least 30 minutes.
  2) Analyze the new tunneling curve and find that the current-piezoelectric ceramic deformation relationship is not just a simple exponential relationship. Based on the teacher’s opinions, it is suspected that there are other functions combined. It is initially suspected that it is caused by the capacitor formed between the tip and the sample.
  3) The fine approach control algorithm has been improved. Now you can click to start the approach and then play a few games of Polar Brawl.
  4) The power supply of the analog part is replaced from a 9V battery to a 3S lithium polymer battery.

• 
  The STM image scanning in constant height mode was completed on 2022/4/20 and verified by repeated experiments, but the complete reliability of the image scale and imaging content cannot be determined.

• 2022/5/01
  Write your graduation thesis.

• On May 4, 2022,
  70% of the graduation thesis was completed, and the constant current scanning algorithm began to be written.

• 2022/6/
  16Second generation microscope open source data released