Friday is here, and the 'Weekend Science Bite' column is back — number 98.
This time: why superpowers are fighting over LED manufacturing technologies.
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The simplicity of an LED bulb conceals some particularly fascinating aspects, both from a physics standpoint and in terms of the wide range of technologies it gives rise to.
An LED is based on semiconductors, much like computer chips.
Chips rely on silicon — a crystal made of atoms with four electrons, where each atom shares its electrons with its neighbors. A pure crystal is a poor electrical conductor, so it is doped with atoms that have three or five electrons, allowing current to flow through it.
But unlike silicon, where electrical current is partly converted into heat, LEDs use specific semiconductors that convert energy into photons of light.
An LED is formed by joining two semiconductor layers — one with an excess of electrons and one with a deficit. Excess electrons that fall into the "holes" of the second layer release the energy gap between their state as free electrons and as bound electrons in the form of photons of light. The color of the light is determined by the energy gap of the electrons in that particular semiconductor.
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LED manufacturing has grown increasingly complex and expensive over time, especially with the shift to gallium nitride as the base semiconductor.
Gallium nitride is a semiconductor that dissipates heat with high efficiency and speed.
This property makes it possible to produce extremely powerful LEDs without burning them out, but it also enables many other applications — including high-power radar systems and antennas operating at very high frequencies.
Gallium nitride's energy gap enables something else unique: an LED that emits white light. Other semiconductors can only produce specific colors, and creating white light previously required combining separate red, blue, and green emitters.
Gallium nitride is an extremely difficult material to manufacture.
It requires access to rare elements and chemical precursors, expensive machines that grow the crystal under precise conditions, and dust-free cleanrooms.
Large LED fabs provide all of this infrastructure, which means their production lines are a perfect fit for manufacturing military technologies that require gallium nitride under identical conditions.
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One example is the Dutch company Lumileds, formerly part of Philips.
The United States previously blocked the sale of the company to China for $3 billion, forcing it to be sold for only $2 billion to an American company instead.
The Chinese recently attempted to acquire the company again through a partnership with a Malaysian firm — a move that was once again blocked by the US government. This time the acquisition offer was just $239 million, after the company had already filed for bankruptcy in 2022.
The company's value lies not in its commercial operations, but primarily in its manufacturing technologies and the countless patents it has accumulated over decades in the field of LED technology. The Chinese covet the company's intellectual property, but there is no chance the United States will ever allow them access to that information.
Shabbat Shalom 😊
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The next column will be published in about two weeks, due to the Shavuot holiday falling on the coming Friday.
In the video: part of the LED bulb manufacturing process | Credit: SatisFactory Process
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