Technology-grade grown diamonds—specifically those produced via Chemical Vapor Deposition (CVD)—are widely considered the “ultimate semiconductor” In high-power electronics, they are moving from being passive cooling components to the active material that handles electricity.
1. Superior Physical Properties
Diamond outperforms current industry standards like Silicon, Silicon Carbide, and Gallium Nitride in almost every metric required for high-voltage environments.
Ultra-Wide Bandgap (5.47 eV): A large bandgap allows diamond to operate at much higher temperatures (up to 500°C or more) and voltages without the material becoming conductive and failing.
Highest Thermal Conductivity: Diamond has a thermal conductivity of roughly 2200 W/m·K, which is 5x higher than copper and 15x higher than silicon. This allows it to pull heat away from active chip areas instantly.
High Breakdown Field: It can withstand electrical fields of roughly 10 MV/cm, allowing for much smaller, thinner devices that can handle kilovolts of power.
2. Primary Use Cases in Power Electronics
A. Passive Thermal Management (Heat Spreaders)
This is the most common use today. CVD diamond plates are placed beneath high-power chips (like those in 5G base stations or radar systems).
The Problem: Traditional chips & “throttle”(slow down) when they get too hot.
The Diamond Fix: Diamond spreaders dissipate “hot spots” across a larger surface area, allowing the chip to run at its maximum rated speed without overheating.
B. Active Semiconductor Devices (Transistors and Diodes)
Engineers are now building the actual electronics out of diamond.
Schottky Barrier Diodes (SBDs): These are used for ultra-fast switching in power grids. Diamond SBDs can handle voltages exceeding 10kV while losing very little energy as heat.
Power MOSFETs: Diamond-based transistors are being developed for Electric Vehicle (EV) inverters. Because they are so efficient, they can reduce the weight of an EV’s cooling system by up to 80%, extending the vehicle’s range.
C. GaN-on-Diamond Technology
This is a “hybrid” approach where a thin layer of Gallium Nitride (the active electronic layer) is grown or bonded directly onto a diamond substrate.
Result: It combines the high-speed electron movement of $GaN$ with the cooling power of diamond. This is the gold standard for high-power radio frequency (RF) amplifiers and satellite communications.
3. Comparison of Material Performance
The following table illustrates why diamond is the target for next-generation systems:
| Property | Silicon (Si) | Silicon Carbide (SiC) | Diamond (C) |
|---|---|---|---|
| Bandgap (eV) | 1.1 | 3.2 | 5.5 |
| Thermal Cond. (W/m·K) | 150 | 490 | 2200 |
| Breakdown Field (MV/cm) | 0.3 | 3.0 | 10.0 |
| Relative Power Handling | 1x | 500x | 20,000x |
4. Current Engineering Challenges
Despite its “super-material” status, two hurdles remain for universal adoption:
Doping: It is notoriously difficult to “dope” diamond (add impurities) to create the type of conductivity needed for many types of transistors.
While boron-doped diamond is well- understood, n-type remains a major research focus.
Wafer Size: While silicon is grown in 12-inch wafers, technology-grade diamond is still typically grown in much smaller squares (often 2-inch or 4-inch), which increases the per-unit cost.