![]() ![]() The mobility in this channel can exceed 1500 cm 2 V -1 s -1, due to the generation of free electrons without impurity doping. ![]() (a) Schematic cross-section of a conventional GaN HEMT and a (b) silicon DMOSFET. One of them already enjoying commercial success is the GaN HEMT, which features a high-density, highly mobile two-dimensional electron gas (2DEG) as a channel, generated by the unique polarisation nature of the AlGaN/GaN heterointerface (see Figure 2(a)).įigure 2. This has led to much interest in devices formed from semiconductors with a wider bandgap. Thus, to deliver higher efficiencies, there’s a need to turn to a different class of semiconductor. Thanks to extensive research and development since the 1960s, their performance has improved, but now it is encroaching material limits. Silicon power transistors are widely deployed in converter applications. Ideally, these devices should combine a low on-resistance, to ensure a low conduction loss in the on-state, with a fast switching performance that trims switching losses. Photograph of fabricated hybrid HEMTs on a 100 mm SiC substrate (left) and an equivalent circuit (right).Īt the heart of power-conversion circuits are power transistors, performing the role of a switch. ![]() To realise this, there will have to be further technological innovation in the power transistors used in the converters.įigure 1. For all these green technologies, we need power converters that are smaller, more efficient and more reliable than the incumbents. Shifting to a low-carbon society will also require an increase in the uptake of electric vehicles, alongside the installation of far more wind turbines and solar farms. Trim the power losses in these converters and boost their efficiency, and this will lead to energy savings at the system level. Such efforts will have to consider the electrical power converters that step up and down the voltage and transfer it from DC to AC or vice-versa – these are the ‘power bricks’, extensively employed in a number of electronic applications, including the power supplies in PCs, telecommunications, electric vehicles and aerospace applications. If we are to move to a greener society, we will need to change the way we produce and use most of our electricity. To succeed, we must act on many fronts, including adopting new approaches to the way that energy is created, distributed and used. Due to this, it is critical that global carbon emissions fall fast. Our planets's temperature is on track to rise to levels that will have horrendous consequences for humanity. ![]()
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