Research Highlights

Exciton-polaritons in atomically thin semiconductors

The Polariton BEC research group (NLPC, RSPhys), led by Prof. Elena Ostrovskaya, uses the ANFF facilities at the ACT node for making all-dielectric optical microcavities with integrated two-dimensional, atomically thin monolayers of transition metal dichalcogenide crystals (TMDCs). In these multilayer heterostructures, photons can couple strongly to the TMDC electron-hole pairs (excitons) and form exciton-polaritons.
Exciton-polaritons can exhibit collective quantum phenomena like Bose-Einstein condensation (BEC) at elevated temperatures. A polariton condensate can behave like a superfluid and propagate without dissipation through a semiconductor. Exploring the superfluidity of polariton condensates and utilising it in novel, energy-efficient optoelectronic devices is one of the goals of the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET).

By Prof. Elena Ostrovskaya

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Hydrogenated amorphous silicon based micro- and nano-photonic structures

Hydrogenated amorphous silicon (a-Si:H) is a versatile platform for electronic and optical applications owing to its distinct physical properties. Recently, it has been widely used in dielectric metasurfaces, leveraging its very high refractive index and wide transmission window spanning from 700nm down to 11µm. As the material properties of a-Si:H film are highly dependent on its preparation history, we have developed various conditions in plasma-enhanced CVD (Oxford, Plasma System 100) suitable for different requirements. Now, we can routinely produce high-quality film (< 1nm surface roughness, <1dB/cm optical loss at near infrared) at low temperature, below 250C. By optimising the film stress via control of the deposition parameters, we are able to coat more than 1µm thick a-Si:H film on glass, sapphire, fluoride, and even plastic substrates. Therefore, the films have been employed in multitude of applications such as color filters in visible range, optical waveguides at telecom band, chemical sensor at mid-infrared, just name a few. The below SEM images represent one example, which is a planar meta-lens operating at 4µm light. The 3mm-diameter lens is composed of numerous 2µm-tall a-Si:H nano-pillars on MgF2 substrate, produced by electron beam lithography (Raith150) and plasma etching (Oxford, Plasma System 100).     

By A/Prof. Duk-Yong Choi

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Advanced designs for perovskite solar cells

We develop advanced perovskite cell architectures, including perovskite-silicon tandem cells. The identification and optimisation of suitable transport layers is critical for this purpose.
We use ANFF facilities to deposit metal oxides such as NiOx and investigate their suitability as transport layers. Currently, the focus is on sputter deposited materials. The sputter parameters need to be carefully tuned in order to ensure optimal device performance. 

By A/Prof. Klaus Webber

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Quantum-well nanowire light emitting devices

In this project we aim to design and demonstrate  III-V compound semiconductor based quantum well nanowire light emitting devices with wavelength ranging from 1.3 to 1.6 μm for optical communication applications.

Prof. Lan Fu, Dr Ziyuan Li, Prof. Hoe Tan, Prof. C. Jagadish AC

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Nanowire arrays for next generation high performance photovoltaics

This is an all-encompassing program to integrate highly sophisticated theoretical modelling, material growth and nanofabrication capabilities to develop high performance semiconductor nanowire array solar cells. It will lead to understanding of the underlying photovoltaic mechanisms in nanowires and design of novel solar cell architectures.

Prof. Lan Fu, Dr Ziyuan Li, Prof. Chennupati Jagadish AC

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UV nano-LEDs

Development of nanowire LEDs for small, robust and highly portable UV sources.

Prof. Chennupati Jagadish AC, Prof. Hoe Tan

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Solar Fuels Generation using III-V Semiconductors

This project aims to develop III-V semiconductors for applicaiton in solar fuels generation.

Dr Siva Karuturi, Prof. Chennupati Jagadish AC, Prof. Hoe Tan

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Solar cells without p-n junctions

Simplify nanowire solar cell fabrication by eliminating the need for p-n junctions to increase the ultimate device efficiency.

Prof. Hoe Tan, Prof. Chennupati Jagadish AC, Dr Kaushal Vora

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Shape engineering of semiconductor nanostructures for novel device applications

This project aims to investigate the growth of III-V semiconductors on pre-patterned nanotemplates. By using different shapes and geometries, it is envisaged that these nanostructures will provide novel architectures for advanced, next generation optoelectronic devices.

Prof. Hoe Tan, Prof. Chennupati Jagadish AC

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Ultra-compact nanowire lasers for application in nanophotonics

This project aims to investigate the concepts and strategies required to produce electrically injected semiconductor nanowire lasers by understanding light interaction in nanowires, designing appropriate structures to inject current, engineer the optical profile and developing nano-fabrication technologies. Electrically operated nanowire lasers would enable practical applications in nanophotonics.

Prof. Chennupati Jagadish AC, Prof. Hoe Tan

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Micro-ring lasers for integrated silicon photonics

The project aims to investigate compound semiconductor micro-ring lasers on silicon substrates using selective area growth to engineer the shape of the lasing cavity at the nano/micro-scale. This project will open up new doors to the industry since an integrated laser which is reliable, efficient and easily manufacturable is still elusive in Si photonics.

Prof. Hoe Tan, Prof. Chennupati Jagadish AC

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Novel composite solid-state nano-pore membranes

High-energy ion irradiation and chemical etching provides an industrially compatible technology for the fabrication of extremely small nano-pores, so-called ‘ion track etched pores’, in silicon dioxide (SiO2) and silicon nitride (Si3N4). Combining this technology with 2D materials such as Graphene and ultra-thin film deposition enables the fabrication of nano-pore membranes with desired functionalities that can be used in medical and biological sensors, ultrafiltration and lab-on-the-chip applications.

We have fabricated track-etched conical and double conical nano-pores in thin SiO2 and Si3N4 membranes. We first deposit SiO2 on Si wafers using plasma-enhanced chemical vapour deposition and then selectively remove the substrate in an area of size 0.55 mm x 0.55 mm using standard Micro-Electro-Mechanical Systems processing. The membranes are then irradiated with 185 MeV and 1.6 GeV Au ions at the 14UD Pelletron Accelerator at the Australian National University and the UNILAC Linear Accelerator at GSI Helmholzzentrum für Schwerionenforschung, respectively. This leads to the formation of ion tracks which are subsequently etched using hydrofluoric acid in a custom-built etching cell to form nano-pores. High precision tuning of the pore dimensions has been enabled by accurate characterisation using synchrotron based small-angle x-ray scattering measurements. Such nano-pores have superior mechanical, chemical and thermal stability and robustness compared to their biological counterparts. These membranes can be easily integrated in solid-state devices for a number of applications. Here, at the Department of Electronics Materials Engineering, Australian National University, we will be using these membranes for chemical and biological molecular measurements, ion rectification, water filtration, ion gating and chemical- & bio-sensing.

Swift Heavy Ion Materials Group

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