A Study of Gallium Nitride Electronics and its Wider Impact on the EconomyOn November 15, 2020 by Jad Dao
Gallium Nitride or GaN, has been at the forefront of semiconductor advancements in recent years with its unparalleled ability to improve power delivery, wireless communications and processing. Gallium in its pure form is not particularly useful, due to its melting point being incredibly low. However, it forms some useful compounds in Gallium Arsenide and Gallium Nitride, the former being widely used as radio amplifiers in cell phones. Gallium Nitride on the other hand, achieved fame in 1993 when Shuji Nakamura used GaN to build the world’s first blue light LED which in turn led to the invention of Blu-ray. The blue LED (when mixed with indium and a yellow phosphor) then led to the white LED which is what’s widely used in today’s lighting and television screens.
As a semiconductor, GaN is interesting since it can operate at much high temperatures. Most computers try to keep their chips at 100 Degrees Celsius or below. Too much above that and the heat can start flipping transistors on at random, causing glitches or damaging the chip. GaN, on the other hand, can operate at up to 300 Degrees Celsius or even higher. GaN also has a significantly higher breakdown voltage than Silicon, this is the voltage where a transistor can’t block the flow of electricity anymore. This allows for you to make a GaN chip the same size as a silicon one which can handle a much larger voltage or allows for a reduction in chip size. It also has very low resistance to current flowing through it meaning it it produces very little waste heat and as a transistor it has a very fast switching speed between on and off which makes it very suited to power electronics. From a physics perspective we’re already approaching silicon’s maximum potential limit but GaN may theoretically be a thousand times more efficient than silicon, enabling much smaller charging devices that hardly waste any power paving the way for electronics with extremely high efficiency.
The industry’s long-term goal to achieve nearly lossless power conversion would be viable through replacing a device’s entire charging circuitry with high performance GaN parts. For example, Gallium nitride power electronics would mean that the entire circuitry contained a laptops charging brick could be built into the plug itself or on many smaller devices, the power conversion circuitry could just be built into the device eliminating the need for cables and dongles.
Effect on Current Technology
Servers and data centres currently consume about 3% of the world’s power and therefore more efficient circuitry could have a huge impact on global power usage. Since GaN circuitry would also produces less heat this could potentially make data centres easier to cool, another source of energy savings. Gallium Nitride inverters could also make solar cells cheaper and lighter which would allow for them to be installed in more places. These inverters can even boost range in electric cars by improving efficiency as well as also make electric high-speed rail easier to deploy. In fact, the Tesla Model 3 already uses Silicon Carbide, a material with similar properties to GaN in some of its power circuitry. If Moore’s law has seen processing power double every two years for the past few decades, power electronics have been on more of a 10-year cycle, still improving, just not nearly as fast as the rest of electronics, and gallium nitride might be a material that helps change that. Gallium nitride’s fast switching speed efficiency and ability to handle high temperatures and voltages are actually seeing it already being used in 5G. Gallium nitride has already been used in LTE base stations and in amplification circuitry since it can efficiently produce high frequency, high power signals and because of that it will certainly find its way into the small cell base stations we’re expecting with 5G. With the power draw of 5G antennas in phones also, a concern GaN may provide a solution to is boosting battery life in handsets.
What’s Keeping GaN from Replacing Silicon?
Ultimately, GaN provides faster switching speeds, an increase in power efficiency, the ability to make smaller chips and a capability to operate at higher frequencies A GaN processor built to the same specifications as a current CPU would be several times faster than a silicon device; up to a hundred gigahertz and a lot more energy-efficient. So why did we get stuck with Silicon when GaN has been around all along?
One challenge is that for a long time, the only transistors we could make with it were so-called depletion mode transistors which means that they’re on by default; it takes voltage applied to them to turn them off. For building logic circuits, this style of transistor is much harder to work with, although several researchers have been able to design enhancement mode transistors that can be set to off by default.
The second challenge is that compared to Silicon, GaN is much harder to work with. Silicon is easier to process into giant crystals that we can slice up into wafers and use to make chips. According to UC Santa Barbara’s Materials Department, before the year 2000, no one had been able to develop a GaN crystal with less than a billion defects per square centimetre. These defects where the crystal structure is either missing an atom or has an extra one inserted can degrade performance or even cause manufacturing errors. Current GaN manufacturing can achieve under a hundred thousand defects per square centimetre, but by contrast, high grade Silicon typically has under a hundred. The current process grows a thin layer of Gallium Nitride on top of a Silicon wafer, a process called Epitaxy. This lets the wafer be processed in a normal chip fab, but ideally it would be more beneficial to grow high quality wafers of pure Gallium Nitride. This might necessitate the need to build a whole new type of chip fab and considering how complex and expensive they are, this will take some serious investment.
Impact of GaN on the Economy
In 2017, the global GaN semiconductor industry was valued at USD 711.44 million and is forecast to reach USD 1.842 billion by 2023, a statistic that represents a 17.1% Compound Annual Growth Rate (CAGR). One of the main reasons for GaN’s expanding semiconductor product market is the growing demand for radio frequency in the semiconductor industry and the booming consumer electronics market (especially LED lighting and display). The market demand for tablets, gaming consoles, laptops and TV will also be another point of potential growth for GaN semiconductor products in the consumer electronics industry. However, while consumer electronics has had the largest share in recent years, the maturing market of smartphones and laptops is projected to reduce its speed, paving the way for the growth of other industries such as aerospace and defence.
Furthermore, with the replacement of incandescent lamps in cars with GaN LEDs and the growing need for electric vehicles, the growth pattern for GaN semiconductor devices is increasing in the automotive industry. The number of electric vehicles in use rose from 113,000 in 2012 to 1,209,000 in 2016, according to the IEA. However, one of the main factors that could delay the growth in this global market is the high manufacturing cost of gallium nitride compared to silicon carbide (which is already widely used in Tesla cars).
Lower labour and manufacturing costs in the Asia-Pacific region are other important drivers in this market’s expansion. Asia-Pacific is projected to hold the largest GaN semiconductor market share by 2023, due to the rising production and export of consumer electronic goods from China and Japan. The demand for electric cars in China is one of the largest in the world and is also one of the main NEV (new energy vehicles) markets in the world. Furthering this growth, on 2017, the first production plant outside of the USA was announced by Tesla Motors, to be based in Shanghai. Similar growth has been occurring in India, since under the government’s new proposals to minimise emissions, India has agreed to only selling electric vehicles by 2030. Suzuki, the largest producer of cars in the country, teamed up with Toyota to produce the first electric car in 2019 to aid this endeavour. Moreover, the Indian Government invested 2.5% of its GDP in healthcare this year which will further fuel the need for GaN semiconductors in the healthcare sector. These factors will increase the already present GaN semiconductor market in India.
In addition to the economic potential of the industry, there are also major prospects for energy savings. Annual shipments of lighting goods across the world amount to 60 billion dollars a year, according to the Department of Energy of the United States. 8% of overall energy use in the United States and 22% of electricity use was due to lighting. The most common sources are inefficient incandescent bulbs: they absorb 40% of light energy and only yield 15% of light production. A 50% penetration of LEDs into the lighting market would allow for substantial energy savings of more than 350 TWh to be achieved. At the moment however, the global LED market only accounts for $3.7 billion worldwide, 58% of which is the cellular market and lighting just 5%.
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