Li Quan Feng, Wang Yang, Wang Fang, Hou Yubin, Lu Qingyou
Henan Key Laboratory of Photovoltaic Materials, School of Physics, Henan Normal University, Xinxiang 453007, People's Republic of China.
College of Electronic and Electrical Engineering, Henan Normal University, Xinxiang 453007, Henan, People's Republic of China.
Rev Sci Instrum. 2021 Jan 1;92(1):013701. doi: 10.1063/5.0024802.
The high-bandwidth preamplifier is a vital component designed to increase the scanning speed of a high-speed scanning tunneling microscope (STM). However, the bandwidth is limited not only by the characteristic GΩ feedback resistor R but also by the characteristic unity-gain-stable operational amplifier (UGS-OPA) in the STM preamplifier. Here, we report that paralleling a resistor with the tunneling junction (PRTJ) can break both limitations. Then, the UGS-OPA can be replaced by a higher rate, higher antinoise ability, decompensated OPA. By doing so, a bandwidth of more than 100 MHz was achieved in the STM preamplifier with decompensated OPA657, and a higher bandwidth is possible. High-clarity atomic resolution STM images were obtained under about 10 MHz bandwidth and quantum point contact microscopy mode with a record-breaking line rate of 50 k lines/s and a record-breaking frame rate of 250 frames/s. Both the PRTJ method and the decompensated OPA will pave the way for higher scanning speeds and play a key role in the design of high-performance STMs.
