Gallium arsenide (GaAs)

Gallium arsenide (GaAs) is a III-V compound semiconductor made from gallium and arsenic. Unlike silicon, it efficiently converts electricity into light and handles high frequencies, making it the backbone of laser diodes (VCSELs), LEDs, solar cells, and RF chips used in phones, satellites, and AI data center optical links.

What gallium arsenide is, in plain terms

Gallium arsenide (GaAs) is a **compound semiconductor**: instead of one element like silicon, it combines gallium (group III) and arsenic (group V), which is why GaAs and its relatives are called **III-V semiconductors**. It forms a crystal with a cubic zinc-blende structure and is grown into wafers, then layered (epitaxy) into devices. The single most important fact about GaAs is that it has a *direct bandgap*: it can turn electricity into light efficiently. Silicon, with its indirect bandgap, essentially cannot. That one property is why GaAs underpins most of the world's tiny lasers and LEDs.

How it works and why it differs from silicon

Two properties make GaAs special. First, the **direct bandgap** lets electrons drop in energy and release that energy as a photon (light) — the basis of laser diodes and LEDs. Second, GaAs has very high **electron mobility**, meaning electrons move faster than in silicon. That allows GaAs transistors to switch at higher frequencies with lower power and to tolerate higher temperatures. The trade-offs: GaAs wafers are smaller (commonly 4-inch/100 mm and 6-inch/150 mm versus silicon's 300 mm), more brittle, and far more expensive. So GaAs is never a silicon replacement for logic or memory; it is used precisely where silicon physically cannot do the job — generating light and handling high-frequency radio signals.

Where GaAs shows up: photonics and RF

GaAs has two major application families. In **photonics**, it makes laser diodes, LEDs, and photodetectors. The flagship device is the **VCSEL** (vertical-cavity surface-emitting laser), a cheap, low-power laser that dominates short-reach optical links; GaAs held roughly a 65% share of the VCSEL market. VCSELs also drive 3D facial recognition and LiDAR sensors. In **RF (radio frequency)**, GaAs makes the power amplifiers and monolithic microwave integrated circuits (MMICs) inside smartphones, 5G base stations, radar, and satellites. GaAs solar cells, though costly, deliver the highest efficiency and are standard on spacecraft.

Why GaAs matters for AI and data centers

AI clusters move enormous amounts of data between GPUs, and copper wiring runs out of reach and power efficiency at high speeds. The fix is **optical interconnects** — sending data as light over fiber. For links under ~100 meters, GaAs-based VCSELs are typically the lowest-cost, lowest-power option, and they power the 400G and 800G transceivers used inside data centers. As the industry moves toward **co-packaged optics (CPO)** — placing the optical engine right next to the switch or GPU — GaAs VCSELs are one of the leading light-source options. In June 2026, startup PicoJool announced 200G-per-lane VCSELs aimed at scale-up AI systems, with a roadmap toward 800G, 1.6T, and 3.2T links. Note: for longer reaches, a cousin material, **indium phosphide (InP)**, increasingly competes and is seeing surging AI demand.

The supply chain and who makes it

The GaAs chain runs from raw gallium → single-crystal substrates (wafers) → epitaxial wafers (epiwafers, with the active layers grown on) → device fabs → modules. **AXT, Inc.** ([AXTI](/stock/AXTI)) makes GaAs, indium phosphide, and germanium substrates, with fabs in China; it has reported a sharp recent uptick in InP for data centers. **IQE plc** ([IQE](/stock/IQE)) is the leading independent supplier of compound-semiconductor *epiwafers* and has supplied GaAs epiwafers since 1988, dominating GaAs HBT and pHEMT material. **Sumitomo Electric Industries** (Tokyo: [3105](/stock/3105)) is a major GaAs and InP substrate maker, supplying low-variation wafers for VCSELs and infrared lasers. Device-side players include Coherent (multiple 6-inch GaAs VCSEL fabs) and Broadcom/Lumentum on the photonics side.

What's changing right now

The biggest shift is geopolitical. China produces roughly 98-99% of the world's primary gallium and, in **August 2023**, imposed export licensing on gallium (and germanium); exports fell sharply, and in **December 2024** China banned gallium exports to the US outright — a ban it suspended in November 2025 for one year. That has put a spotlight on gallium as a critical material and on diversifying supply. Commercially, demand is being pulled in two directions: weak smartphone/RF markets have pressured GaAs revenues, while AI-driven optical demand is booming — though much of that incremental AI demand is flowing to indium phosphide as well as GaAs. Market forecasts put the GaAs wafer market growing from roughly $0.44B in 2025 toward $1.1B by 2030.

Frequently asked

Is gallium arsenide better than silicon?

Not in general — they do different jobs. GaAs is far better at converting electricity into light (lasers, LEDs) and at high-frequency RF, and it is faster and more power-efficient there. But it is more expensive, more brittle, comes on smaller wafers, and cannot economically replace silicon for the logic and memory chips that run computers. The two are complements, not rivals.

What is GaAs used for in everyday devices?

Smartphone power amplifiers (the RF front-end that handles 4G/5G signals), the VCSEL lasers behind facial-recognition and proximity sensors, LEDs, fiber-optic transceivers, automotive and consumer LiDAR, and high-efficiency solar cells on satellites.

How does GaAs relate to AI data centers?

AI training clusters need to move huge data volumes between GPUs faster and more efficiently than copper allows, so links are going optical. GaAs-based VCSELs are a leading low-cost, low-power light source for short-reach (under ~100 m) 400G/800G links and for emerging co-packaged optics, making GaAs part of the AI hardware supply chain.

What is the difference between GaAs and indium phosphide (InP)?

Both are III-V compound semiconductors used in photonics. GaAs VCSELs dominate cheap, short-reach optical links, while InP lasers handle longer reaches and the wavelengths (around 1310/1550 nm) used over fiber. AI demand is currently lifting both, with InP seeing especially strong recent growth for data-center interconnects.

Why is China's gallium export control a big deal for GaAs?

China produces an estimated 98-99% of the world's primary gallium, the key input. Its 2023 export licensing and 2024 US ban (suspended in late 2025) raised supply risk for GaAs makers and pushed Western governments and companies to treat gallium as a critical material and seek alternative sources.

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