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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Novel (M,Ga)2O3 thin films for two-dimensional electron gas devices

Alternative title: Nye komponenter for kraftelektronikk basert på Ga2O3med 2D elektrongassegenskaper

Awarded: NOK 8.0 mill.

Project Number:

301740

Application Type:

Project Period:

2020 - 2023

Location:

The aim of the GO2DEVICE project is to develop a new transistor for use in the power electronics sector, which has the potential to become faster, smaller and operate at higher power than existing options. Power electronics (PE) play an important role in the collection, delivery and storage of energy, and is a key enabler for energy efficiency, renewable energy and smart grids. Silicon-based PE components have been optimized to the point where further improvements start to be limited by the materials properties themselves, and in order to meet the needs predicted for a sustainable society, new materials are targeted. Among the newest candidates is gallium oxide (Ga2O3), which is a wide bandgap semiconductor with an ultra-high breakdown field. In the GO2DEVICE project, we will study a special variety of Ga2O3, the so-called kappa-phase. Theoretical calculations suggest that the band structure (a semiconductor characteristics) of this phase may allow for the formation of 2D electron gas, i.e., an interface where electrons can move without resistance. By partially replacing gallium with indium and aluminium, precise tailoring of the materials properties will be pursued, towards fabrication of a so-called high-electron-mobility transistor (HEMT). To accomplish a working prototype, however, close control of structural and electronic properties is of paramount importance. In the GO2DEVICE project, advanced materials characterization and modeling will provide feedback to the materials synthesis in a close international collaboration between young and accomplished scientists. The project progresses according to plan, but at a slightly slower pace due to challenges imposed by the corona situation.

In the GO2DEVICE project, fabrication of a high-electron-mobility transistor (HEMT) based on novel (M,Ga)2O3 thin film heterostructures will be pursued (M = Al, In). (M,Ga)2O3, which is a wide bandgap semiconductor, has recently been stabilised in an orthorhombic phase (k) for Mx=In up to x = ~0.35. Large spontaneous polarization has been predicted for the k-phase, suggesting that interface-localized two-dimensional electron gas (2DEG) can be achieved in substantial concentrations. The precise tailoring of properties, e.g., bandgap and carrier concentrations, enabled by (M,Ga)2O3 alloying, provide a wide parameter space for device development and optimization. To accomplish a working prototype, however, close control of structural and electronic properties is of paramount importance. In the GO2DEVICE project, advanced materials characterization and modeling will provide input to the materials synthesis in a close international collaboration between young and accomplished scientists. Synthesis of good-quality epitaxial layers with strain engineered interfaces will be aided by transmission electron microscopy (TEM). The band structure of k-(M,Ga)2O3 as a function of composition will be investigated by photoemission spectroscopy (PES) techniques, such as X-ray photoelectron spectroscopy (XPS) and angular resolved PES with high spatial resolution (micro-ARPES), aided by density functional theory (DFT) calculations. The PES measurements, together with charge transport investigations, will play a crucial role in the device design process. The ambition of the GO2DEVICE project is to establish a complimentary framework for knowledge-based device design and fabrication, all the way from state-of-the-art fundamental science to working prototype device. If successful, the development of a high-electron-mobility transistor (HEMT) device based on k-phase (M,Ga)2O3 thin film heterostructures will represent a breakthrough for Ga2O3 electronics.

Activity:

FRINATEK-Fri prosj.st. mat.,naturv.,tek