Somewhere in the last few years, chargers quietly shrank. A 65-watt charging block that used to take up half an outlet strip now fits next to your keys. The battery inside your phone didn't get this upgrade, the semiconductor switching the power did.

Interior photo of a disassembled silicon-era power adapter, showing a large copper-wound transformer and bulky capacitors
Inside a silicon-era power adapter — the large copper-wound transformer is most of the bulk. Reise Reise, CC BY-SA 4.0, via Wikimedia Commons.

The transformer is the problem

A charger's job is to take wall power and step it down to something your device can use, and it does this by switching the incoming power on and off at high frequency through a small transformer, thousands to millions of times a second. The faster you can switch, the smaller the transformer and supporting coils can be — size scales down roughly in proportion to frequency.

Block diagram of a switch-mode power supply's functional stages
The basic functional stages of a switch-mode power supply. Dlrohrer2003, CC BY-SA 3.0, via Wikimedia Commons.

The limiting factor has always been the switching transistor. Ordinary silicon MOSFETs lose more energy as heat the faster you switch them, and that heat has to go somewhere — usually a bigger heatsink and a bigger enclosure to dissipate it safely. For decades, that tradeoff capped how small a charger could get at a given wattage.

A wider bandgap changes the math

Gallium nitride (GaN) is a wide-bandgap semiconductor, which in practice means it can switch far faster than silicon while wasting much less energy doing it. Higher switching frequency lets the transformer and inductors shrink dramatically; lower switching losses mean less heat, which means a smaller enclosure and a smaller (or absent) heatsink. Both effects push in the same direction: less silicon-era bulk, for the same or higher wattage.

Chart comparing electronic bandgap energy in electron volts for various semiconductors, including silicon, silicon carbide, and gallium nitride
Bandgap energy across common semiconductors — silicon at 1.12 eV, silicon carbide at 2.42 eV, gallium nitride at 3.2 eV. Cmelni, CC BY-SA 4.0, via Wikimedia Commons.

That's the whole story behind the wave of tiny 65W and 100W GaN chargers that showed up on charging blocks over the past few years — not a new battery trick, a better switch.

Cross-sectional electron energy band diagram of a High Electron Mobility Transistor, the device structure GaN power transistors use
The band structure of a High Electron Mobility Transistor (HEMT) — the device architecture behind GaN power transistors. Cepheiden / sfu, CC BY-SA 3.0, via Wikimedia Commons.
Worth being precise here too, same way the SiC/Si-C mix-up comes up in battery anodes: gallium nitride and silicon carbide (SiC) are both wide-bandgap semiconductors, but they specialize differently. SiC tends to win at higher voltages and power levels — EV inverters, industrial drives. GaN tends to win at higher frequencies and lower-to-mid power — chargers, power supplies, RF amplifiers. Related chemistry, different jobs.

Not just smaller — cooler and cheaper to run

Lower switching losses mean a GaN charger wastes less power as heat for the same job, which matters more at scale than it sounds: a data center's worth of power supplies running a percent or two more efficiently adds up fast. On your desk it just means the brick barely gets warm anymore.

Photograph of an actual gallium nitride monocrystal specimen
A gallium nitride monocrystal — the actual material behind all of this. Opto-p, public domain, via Wikimedia Commons.

What to watch

  • Prices keep dropping as GaN fabrication scales — it was a premium feature a few years ago, now it's showing up in budget chargers.
  • Multi-port chargers pushing higher combined wattages (100W+) without getting bigger, since GaN is what makes splitting power across ports efficiently practical.
  • GaN creeping into laptop power supplies and eventually server/data-center power delivery, where the efficiency gain matters even more than the size.

Same pattern as the anode story: not a flashy headline feature, just a components-level swap that quietly makes everything around it smaller, cooler, and a little more efficient.

Further reading

  1. Udabe, A., Baraia-Etxaburu, I., & Garrido Diez, D. "Gallium Nitride Power Devices: A State of the Art Review." IEEE Access, 11, 48628–48650 (2023). DOI: 10.1109/ACCESS.2023.3277200
  2. Pushpakaran, B.N., Subburaj, A.S., & Bayne, S.B. "Commercial GaN-Based Power Electronic Systems: A Review." Journal of Electronic Materials, 49, 6247–6262 (2020). DOI: 10.1007/s11664-020-08397-z
  3. Mishra, U.K. "Gallium Nitride Versus Silicon Carbide: Beyond the Switching Power Supply." Proceedings of the IEEE, 111(4), 322–328 (2023). DOI: 10.1109/JPROC.2023.3254279
  4. Buffolo, M., Favero, D., Marcuzzi, A., et al. "Review and Outlook on GaN and SiC Power Devices." IEEE Transactions on Electron Devices, 71(3), 1344–1355 (2024). DOI: 10.1109/TED.2023.3346369
  5. Rafin, S.M.S.H., Ahmed, R., Haque, M.A., et al. "Power Electronics Revolutionized: A Comprehensive Analysis of Emerging Wide and Ultrawide Bandgap Devices." Micromachines, 14(11), 2045 (2023). Open access. pmc.ncbi.nlm.nih.gov
  6. Ponnambalam, R., & Vairavasundaram, I. "GaN-Based DC-DC Converters for EV Fast Charging: A Review." Results in Engineering, 28, 107548 (2025). DOI: 10.1016/j.rineng.2025.107548
  7. Texas Instruments. "TI expands low-power GaN portfolio, enabling AC/DC power adapters to shrink 50%." (2023). ti.com
  8. Efficient Power Conversion Corporation. "GaN for DC-DC Conversion — Buck Converters." Reference design guide. epc-co.com
  9. "Navitas' GaN and SiC devices adopted in Dell's family of 60–360W AI notebook adapters." Semiconductor Today (2025). semiconductor-today.com
  10. Dagher, R. "From Chargers to Data Centers: Power GaN Market Set for Rapid Sixfold Expansion by 2030." Yole Group (2025). yolegroup.com
  11. Alqarqaz, Q. "Gallium Nitride: The Ideal Semiconductor for Power-Hungry Electronics." IEEE Spectrum (2019). spectrum.ieee.org
  12. Zorpette, G. "Is This Hybrid Tech the Future of Power Electronics?" IEEE Spectrum (2024). spectrum.ieee.org
  13. Brookes, T. "What Is a GaN Charger, and Why Will You Want One?" How-To Geek. howtogeek.com
  14. Bonk, L. "Why bulky laptop chargers are a relic of the past." Engadget (2026). engadget.com