Mid-infrared photodetectors based on atomically thin 2D materials

This joint PhD project is based at The University of Melbourne with a 12 month stay at the Shanghai Jiao Tong University.

The main objectives of this project are to:

• Develop room-temperature mid-infrared photodetectors based on atomically thin MoS2 monolayers.
• These photodetectors will in turn be used to develop a miniature infrared spectrometer chip.

The details

This joint PhD project is based at the Shanghai Jiao Tong University with a 12-month stay at The University of Melbourne.

Project description:

Mid-infrared photodetectors have a wide range of applications in many fields. The existing mid-infrared photodetectors have to operate at cryo temperature, as a result of which systems for mid-infrared photodetection and imaging are often bulky and expensive.

In this study, we propose to develop room-temperature mid-infrared photodetectors based on atomically thin MoS2 monolayers. These photodetectors will in turn be used to develop a miniature infrared spectrometer chip.

Atomically thin monolayers are poor light absorption materials. To enhance the light absorption, we propose to place the monolayer on a bulk HgCdTe crystalline substrate that absorbs mid-infrared light. The light absorption in HgCdTe substrate with a junction (induced by surface charges or doping) will create a photovoltage gating on the MoS2 monolayer. We will read this out electrically, i.e. by measuring the change in conductivity of the MoS2 monolayer.

Since the MoS2 monolayer has a wide bandgap, it can operate in the subthreshold region, meaning that the dark current will be suppressed. The fact that the MoS2 monolayer is atomically thin will allow the weak photovoltage to gate the monolayer in an effective manner and induce a large conductivity change. We anticipate that this will result in this device having a very high gain (>10^8) and a high photoresponsivity.

The project will be complemented by the project 'Novel photodetectors based on nanomaterials: devices and applications' and the collaboration will ensure the successful completion of the project.

Supervision team

Associate Professor Yaping Dan (Shanghai Jiao Tong University)

Professor Kenneth Crozier (The University of Melbourne)