Page 20 - PEN eBook December 2022

SEMICONDUCTORS Semiconductors

To maximize the potential of a novel semiconductor technology, the industry must make a concerted
effort to solve technical obstacles that hinder performance. Significant technological advancement
has taken place in the field of ultra-wide–bandgap semiconductors since 2016, when Flosfia, a

spinoff from Kyoto University specialized in R&D and commercialization of gallium oxide thin films,
concluded that gallium oxide warranted development.

The semiconductor industry is increasingly moving toward implementing devices built from
wide-bandgap materials such as silicon carbide and gallium nitride, but the cost of those materials
remains relatively high. In response, researchers more recently have pursued development of
beta-gallium oxide (β-Ga O ), a stable phase of the compound. β-Ga O development is a
2 3 2 3
result of an increased focus on materials research to improve the overall performance of
power-electronic devices over the junction-based approaches of the past. β-Ga O stands out for its
2 3
intrinsic properties, including an ultra-high bandgap (an energy gap of 5 eV), good conductivity and
field-holding capacity, and high critical field strength, with the highest ever demonstrated being
5.5 MV/m.

Processing the material in different ways can result in a variety of properties, demonstrating its
flexibility. For example, doping the material from a melt results in a resistivity of 10 mΩ-cm; silicon
implantation can decrease it to 1 mΩ-cm. Halide vapor epitaxy on the material can be controlled to

have a doping concentration in the range of 10 to 10 cm .
19
–3
15
Fabricating standard
features onto β-Ga O
Gallium Oxide: A is also relatively easy.
3
2
For example, ohmic and
Next-Gen Schottky contacts can
be made using standard

Semiconductor for metals like titanium,
aluminum, and nickel at
relatively low annealing
Power Devices temperatures.

Wafering and lapping of
By Maurizio Di Paolo Emilio the material can be done

using standard production

In the past decade, gallium oxide has seen fast technical development, propelling it to the forefront tools. Different dielectric Figure 1: A top-level view of the technology progress for various sectors toward
of ultra-wide–bandgap semiconductor technologies. The major targeted application space is power materials, such as Al O commercialization of β-Ga O applications as of October 2021 (Source: Link)
2
3
2 3
electronics, in which gallium oxide’s intrinsic material properties — high critical field strength, deposited using the
widely tunable conductivity, low mobility, and melt-based bulk growth — promise to deliver the atomic layer deposition method, can be used as gate dielectrics (Figure 1).
required high performance at low cost.

36 DECEMBER 2022 | www.powerelectronicsnews.com DECEMBER 2022 | www.powerelectronicsnews.com 37