There are exacting demands now being placed upon the manufacturers of consumer electronics goods, as they strive to provide their customer base with more streamlined, sleeker products that also have the capacity to sustain longer periods between battery recharges. Likewise, legislative guidelines are pushing datacenters to become more power efficient and support an intensified concentration of electronics hardware. These issues, amongst others, mean that the industry is being compelled to adopt new semiconductor materials, so that components can be produced which have higher power conversion efficiencies, faster switching speeds and greater power densities.
Though silicon (Si) has of course been the foundation of semiconductor advance for many decades, in power electronics its value may be starting to diminish, as we reach the physical limits of what this material can actually achieve. Performance improvements will be at best minor - way beyond what is certain to be asked of power IC manufacturers in the next few years.
Gallium nitride (GaN) is now coming to the fore, possessing many characteristics that will allow production of power transistors which outperform Si devices. GaN has wider band gap and a considerably higher critical electric field, as well as very high electron mobility. These advantages offer power electronics engineers the opportunity for superior power density since GaN offers the same level of performance as Si while fitting into a much more compact area. This is of particular benefit under ever greater space constraints. Through the high mobility of GaN, higher switching speeds can be derived, with the upshot that fewer passive components are needed for the accompanying power circuitry, once again saving space, as well as reducing overall system cost.
The extremely low losses of GaN allow significantly improved efficiency in power conversion systems compared to those possible with silicon devices. Unfortunately, GaN’s prohibitive production costs have until this point swayed things in Si’s direction - as the cost effectiveness of Si has made up for its poorer functional performance.
Though the expense involved in fabrication has previously been a hindrance, a number of technological and commercial factors are now bringing GaN further and further into favor.
The GaN production procedure is being improved all the time, enabling yield figures to be raised. It is predicted that once migration to GaN within the power electronics sector begins then the whole thing is destined to snowball, just like it did for silicon back in the late 1960s. Economies of scale will lower the associated price tag of GaN power products, this will open up new opportunities, thus increasing demand and subsequently dragging unit costs down still further.
Since Si fabrication is already moving, with increasing frequency, on to 300 mm wafers, GaN production will be able to take advantage of the manufacturing capacity that has been freed up - utilizing the manufacturing sites and equipment that would otherwise be left redundant. As a result, GaN production can exploit existing infrastructure that has already been paid off, rather than warranting completely new investment in capital equipment and facilities.
GaN will make a major contribution to next generation power system design in a variety of different markets, including consumer electronics, data communications and automotive. Server racks will be able to incorporate greater processing capacity as less board real estate will be needed for thermal management mechanisms to accompany the power electronics. Items of portable electronics will be more compact, while at the same time having more expansive battery lives. Electronics systems will be able to cope much better with the high voltages and elevated temperatures found in automotive environments. The semiconductor manufacturers that are already allocating engineering resources to this process technology, and entering into mutually beneficial technology partnerships, will be the ones that are best able to respond to the GaN migration when it occurs. ON Semiconductor is collaborating with Transphorm in order to develop a new breed of GaN-based power solutions that will fully address future power system demands.