ADI KUMAR · POWER & DIGITAL INFRASTRUCTUREJULY 2026 · V2 · ~50 MIN READ
The AI Power Chain · Part II of IV
Market deep dive · Wide-bandgap semiconductors

The Wide-Bandgap Stack: Boom, Bust, and the Rebuild of AI's Power Semiconductor Chain

SiC and GaN are the enabling materials of the 800VDC data center. Their industry has just come through a capacity glut, a 60%+ price collapse, and the Chapter 11 filing of Wolfspeed, its founding US pure-play. This piece works down the chain from crystal boule to gate driver: who makes what, where the chokepoints sit, why the demand boom and the bust arrived at the same time, and what the rebuild means for capital.

By Adi Kumar Independent analysis Views are my own
Executive summary. Nine findings.
  1. The bust-boom overlap. Wolfspeed emerged from Chapter 11 in September 2025 having cut ~$4.6B of debt (~70%). Over the same period its AI data center revenue doubled in three quarters. The bust was automotive; the boom is data center, and they overlapped.
  2. Prices collapsed, not demand. 6-inch SiC epi wafers fell from $600+ (early 2023) to ~$400 by 2025. Chinese 6-inch spot was reported near $200 in mid-2026 on a single trade-press source, not corroborated in Western procurement quotes at time of writing. 8-inch declines exceeded 60% across multiple sources. Chinese substrate capacity went from 460k units (2022) toward a projected 7.7M by 2027.
  3. AI is re-rating the whole chain. Infineon guides AI-related revenue from €1.5B (FY26) to €2.5B (FY27) and sizes the AI power opportunity at ~€12B by 2030. onsemi says content per 1MW AI rack doubled from ~$50k to ~$100k.
  4. Content escalation is the core investable fact. Power component content per rack rises roughly 4x from GB200 to Vera Rubin and ~11.5x to Rubin Ultra. That is a BOM restructuring, not a cyclical uptick.
  5. SiC and GaN divide by physics. SiC owns high-voltage grid-to-rack conversion. GaN owns high-frequency intermediate and point-of-load stages. Navitas' 800V-to-6V board that eliminates the 48V intermediate bus is the clearest signal of where GaN is heading.
  6. Substrates are commoditizing; packaging is not. The scarcity has migrated downstream to AMB silicon-nitride substrates, sinter pastes, and thermal materials, where Japanese and German suppliers hold ~85% share and Si₃N₄ is >95% of the AMB mix.
  7. Gallium is a Chinese export instrument. China's export controls on gallium put GaN's raw-material base under policy risk that SiC's does not carry. The asymmetry between the two technologies is underpriced.
  8. The M&A window is wide open. A post-restructuring Wolfspeed, sub-scale GaN specialists, and distressed Chinese substrate capacity meet buyers (Infineon's "30-30" ambition, onsemi, Renesas, Samsung) who need capacity and design-ins fast.
  9. Bottom-up TAM. WBG devices in AI data centers at roughly $1.5–2.5B in 2026 scaling to $9–14B by 2030 in the base case. The bull case is gated by qualification, not by silicon.
BOULEStage 0 · Wolfspeed
The AI Power Chain · six essays, one physical arc

The series walks a single physical path. It begins at the medium-voltage utility bus at the site fence, steps down through the substation and switchgear, arrives at the datacenter rack where 800V DC is stabilised by the capacitor stack, is converted by silicon-carbide switches to 48V, is distributed across the rack by copper busbars and whips, is stepped down again by multi-phase controllers on the accelerator board to 0.8V, and finally routed through the on-package power delivery network to a transistor gate drawing over 2,000 amperes. Waste heat from every conversion stage is removed by the thermal stack. The whole thing is packaged inside a factory-modular building because there aren't enough electricians to build it stick-frame. Six essays. One 800V → 0.8V staircase.

  1. Part I. The Capacitor Stack — 800VDC at the rack
  2. Part II. The Wide-Bandgap Stack — SiC and GaN conversion (you are here)
  3. Part III. The Thermal Stack — removing the waste heat
  4. Part IV. The Interconnect Stack — busbars and whips
  5. Part V. The On-Package Delivery Stack — 48V to 0.8V
  6. Part VI. The Modular Datacenter Stack — how the building gets built
~11.5x
Power component content per rack, GB200 to Rubin Ultra
€2.5B
Infineon's FY2027 AI-related revenue target, up from €1.5B in FY2026
The price collapse that defined the cycle
Discrete published price observations, USD per 6-inch wafer, 2023–2026. Note: the series mixes epi-wafer and bare-substrate quotes from different sources. It is a set of observations, not a like-for-like index.
[A1] Woodside Capital Partners (Jun 2025) for 2023 epi-wafer points; eeNews Europe (Nov 2025) for 2024–25 substrate points; DigiTimes via industry press (Jun 2026) for the Chinese spot figure (single-source, unconfirmed). See Annex §A1 for the full reconciliation.
MAPThe framework · Eight layers, one chain

The wide-bandgap value chain, layer by layer

The capacitor stack divides by timescale. The wide-bandgap chain divides by process step. Each step has a different competitive structure, capital intensity, and margin profile, and the AI transition is redistributing power between them. The map below names the players at every layer. Two things to notice before reading it: the extraordinary Japanese depth in materials and packaging, and how thin the qualified supplier base becomes at the ceramic-substrate and sinter-paste layers. Those are the chokepoints most investors miss because they are looking at wafers.

The wide-bandgap power semiconductor market map
Named players by layer · leaders highlighted · July 2026
L1Crystal growth & substratesPVT boule growth, slicing, polishing · 150/200mm, first 300mm demo
Wolfspeed US · ~34%
TanKeBlue CN · ~17%
SICC CN · ~17%
Coherent US · ~14%
SiCrystal (ROHM) DE/JP
SK Siltron CSS KR
Sanan Optoelectronics CN
Synlight Crystal CN
JSG / Jingsheng CN
GlobalWafers TW
Soitec (SmartSiC) FR
onsemi (ex-GTAT) US · captive
ST (ex-Norstel) EU · captive
L2EpitaxyDoped SiC/GaN layers · the yield-critical step · mostly captive, partly merchant
Wolfspeed US · merchant
Epiworld CN
Hantian / Enkris CN
IQE UK · GaN/RF
Episil / EpiCrystal TW/CN
NexWafe-adjacent EU
L3aSiC device makersMOSFETs, diodes, JFETs · 650V to 3300V · top five ≈ 90% of revenue
STMicroelectronics EU · #1
onsemi US
Infineon DE
Wolfspeed US
Bosch DE
Nexperia NL
Microchip US
Littelfuse (IXYS) US
Vishay US
Navitas (GeneSiC) US · 2.3/3.3kV
Qorvo JFET → onsemi US
BYD Semiconductor CN
United Nova (UNT) CN
BASiC Semiconductor CN
AccoPower CN
SemiQ US
L3bGaN device makers100V–650V HEMTs and power ICs · top five ≈ 88% · the AI-rack growth engine
Innoscience CN · ~30%
Infineon (GaN Systems) DE
Power Integrations US
Navitas US
EPC US
STMicroelectronics EU
Texas Instruments US
onsemi US · entering
Samsung KR · 2026 entry
Cambridge GaN Devices UK
VisIC IL
Nexperia NL
MACOM · Qorvo US · RF GaN
L3cFoundriesMerchant WBG wafer capacity · the fabless enabler
GlobalFoundries US · Navitas partner
PSMC · Powerchip TW
Vanguard (VIS) TW
X-FAB EU
Polar Semiconductor US
TSMC TW · exiting GaN
Samsung Foundry KR
CR Micro · Silan CN
L4Packaging materialsAMB/DBC ceramic substrates, sinter pastes, die attach, bond wire · top 8 ≈ 85%
Rogers (curamik) US/DE
Heraeus Electronics DE · ~15%
Xinzhou Electronic CN
Zhejiang TC Ceramic CN
BYD CN · captive
KCC · Amogreentech KR
Indium Corporation US · sinter
MacDermid Alpha US · sinter
Henkel DE · TIM/attach
L5Power modules & convertersHalf-bridges, IPMs, DC-DC bricks, PSUs, rack power boards
Infineon DE · modules+POL
Semikron Danfoss DE/DK
Vincotech EU
Monolithic Power (MPS) US · VRM
Vicor US
Analog Devices US
Texas Instruments US
Delta Electronics TW
Lite-On TW
Flex · Celestica US/CA
Vertiv US
Schneider Electric FR
ABB CH/SE
Navitas PDB US · 800V→6V
Littelfuse US · protection
L6Capital equipmentThe picks-and-shovels of the picks-and-shovels
Axcelis (Purion) US · SiC implant
Aixtron DE · epi
LPE IT · epi
Veeco US
Applied Materials US
KLA · Onto · Bruker US · metrology
Revasum US · CMP
Siltectra/Infineon cold split DE · captive
AMEC · NAURA CN
JapanUnited StatesEuropeChinaKoreaTaiwanShaded tiles = category leaders
How to read this map. The shares quoted are approximate and drawn from public research of differing vintages and scopes. Treat them as positional, not precise. Company names are set as text, not logos. Several firms appear at multiple layers, which matters structurally: vertical integration is the dominant competitive strategy, and the companies that survived the glut are disproportionately the ones that owned their own substrate supply.
L1Crystal growth & substrates