Gallium nitride, or GaN, is a material that's starting to be used for semiconductors in chargers. It was used to make LEDs starting in the '90s, and it's also a popular material for solar cell arrays on satellites. The main thing about GaN when it comes to chargers is that it produces less heat. Less heat means components can be closer together, so a charger can be smaller than ever before—while maintaining all the power capabilities and safety standards.
Before we look at GaN on the inside of a charger, let's take a look at what a charger does. Each of our smartphones, tablets, and laptops has a battery. When a battery is transferring power to our devices, what's happening is actually a chemical reaction. A charger takes an electrical current to reverse that chemical reaction. In the early days, chargers just sent juice to a battery constantly, which could lead to overcharging and damage. Modern chargers include monitoring systems that lower the current as a battery fills up, which minimizes the possibility of overcharging.
Since the '80s, silicon has been the go-to material for transistors. Silicon conducts electricity better than previously used materials—such as vacuum tubes—and keeps costs down, as it's not too expensive to produce. Over the decades, improvements to technology led to the high performance we're accustomed to today. Advancement can only go so far, and silicon transistors may be close to as good as they are going to get. The properties of silicon material itself as far as heat and electrical transfer mean the components can’t get any smaller.
GaN is different. It's a crystal-like material that's capable of conducting far higher voltages. Electrical current can pass through components made from GaN faster than silicon, which leads to even faster processing. GaN is more efficient, so there's less heat.