Post-doc position : Development of Novel Cooling Devices Based on Semiconductor Heterostructures

Limit to apply through ABG website : 2019-09-02

starting : between 2020-04-01 and 2020-09-30

Duration : 1 year or 2 years 

Application through ABG website : ABG87023


The principal investigator and his colleagues at Institute of Industrial Science (IIS), University of Tokyo, are working on novel solid-state cooling devices based on semiconductor quantum heterostructures. Nanoscale miniaturization of semiconductor devices has led to major advances in opto/nanoelectronics.  However, this device downscaling also brought technological issues. Among them, one of the most detrimental is the self-heating effect, which results in significant reduction in performance and lifetimes of the devices.  On the other hand, the refrigeration of the entire systems is extremely power consuming.  The engineering of efficient cooling is, therefore, one of the major scientific, technological and environmental tasks in a context of energy resource shortage.

We are interested in realizing novel solid-state devices based on the concepts of “thermionic and evaporative cooling” to efficiently refrigerate lattice and electron systems, respectively. 

We have recently demonstrated that III-V quantum heterostructure can provide a remarkable electron cooling effect by 50 K at room temperature [1].  The aim of this project is to further improve electron cooling and to show comparable achievement for lattice refrigeration.

  The project consists of (1) the fabrication of solid-state refrigeration devices using GaAs-based heterostructures and (2) the development of new temperature sensing method using photoluminescence and micro-electromechanical systems (MEMS) structures [2].  By doing so, we will demonstrate a novel possibility of efficient cooling devices. The prospective postdoctoral researcher is expected to join and pursue this project.

The laboratory is well equipped with nanofabrication apparatus and measurement setups. Furthermore, the group as also expertise in quantum transport calculations, which will support the project from the theoretical side [3].


[1] A. Yangui, M. Bescond, T. Yan, N. Nagai, K. Hirakawa, “Evaporative electron cooling in asymmetric double barrier semiconductor heterostructures,” submitted to Nature Commun. (2019).

[2] Y. Zhang, Y. Watanabe, S. Hosono, N. Nagai, and K. Hirakawa, “Room temperature, very sensitive thermometer using a doubly clamped microelectromechanical beam resonator for bolometer applications” Appl. Phys. Lett108, 163503 (2016).

[3] M. Bescond, D. Logoteta, F. Michelini, N. Cavassilas, T. Yan, A. Yangui, M. Lannoo, K.  Hirakawa, “Thermionic cooling devices based on resonant-tunneling AlGaAs/GaAs heterostructure,” J. Phys.: Condens. Matter 30, 064005 (2018).

  • Fellowships are tenable for a period of between 12 and 24 months and must start in Japan during the period of 1 April 2020 – 30 September 2020


Candidates are expected to have a background of solid state physics and/or device physics, and have interests in nanotechnologies/nanosciences.  Skills on microfabrication and small signal measurements will be helpful.  A challenging sprit would help a lot for tackling this interdisciplinary and cutting-edge research area.


The prospective postdoctoral researcher should understand the concept of the thermionic/evaporative cooling and learn experimental details, such as sample fabrication, electrical and photoluminescence characterization.  Then, he or she is supposed to start a more systematic work on the dependence of the electron cooling on the structural parameters in order to optimize the device structures.  Furthermore, measurements on the lattice cooling effect in very thin layers (the quantum wells) will be attempted by developing a novel temperature sensing method using MEMS structures. Experimental results obtained by the postdoctoral researcher will also benefit from quantum transport modeling in order to answer fundamental questions and to speed up the optimization of nanodevices providing the highest cooling efficiency.