Home‎ > ‎Research‎ > ‎

Fast probe of local electronic states in nanostructures utilizing a single-lead quantum dot

Introduction

Local electronic states in solid state nanostructures attract much interest in basic science and device applications. To probe the local states, various methods have been developed.

In this experiment, we realize a fast probe of the local electronic states utilizing a semiconductor quantum dot and high frequency measurement techniques. 


Experiment

The left picture shows a scanning electron micrograph of the device. A probe quantum dot is formed at the position of the blue circle. We can probe the local electronic sates by monitoring electron tunneling into this dot.

The electron tunneling is monitored by the reflection measurement of the high frequency signals. This new technique enables us to resolve a single electron charge in 5 micro seconds. This speed is almost 1000 times faster than the conventional transport measurements.

The right graph shows time traces of the signal reflecting the electron tunneling into the dot.














Next, we form another target quantum dot and probe the inner electronic states of the dot. We detect discrete energy levels formed in the quantum dot corresponding the black lines in the left graph.

This measurement scheme is more robust compared to the conventional methods. The signals are robust against bias voltages and electron temperatures.

The right graph shows real time movements of the electrons in the target quantum dot. This fast probe can access dynamics in small structures.



Conclusion

We have realized a fast probe of local electronic states in nanostructures utilizing a quantum dot and high frequency measurement techniques. We demonstrated the operation and good properties of the new probe.

These results will be important for exploring local electronic states in nanostructures and future applications to new electronic devices.


Reference

Fast probe of local electronic states in nanostructures utilizing a single-lead quantum dot”,
Tomohiro Otsuka, Shinichi Amaha, Takashi Nakajima, Matthieu R. Delbecq, Jun Yoneda, Kenta Takeda, Retsu Sugawara, Giles Allison, Arne Ludwig, Andreas D. Wieck, and Seigo Tarucha,