The Two Common Semiconductor Materials Are Silicon and Silicon Carbide: A Technical Comparison

A semiconductor is a solid material with electrical conductivity between that of a conductor and an insulator, which can be precisely controlled via doping, temperature, or applied electric fields. Many engineers assume the two common semiconductor materials are and always will be silicon and germanium, but modern power electronics has entirely shifted. Today, the real battle for high-efficiency design is between standard Silicon (Si) and wide-bandgap Silicon Carbide (SiC). Choosing between them dictates your circuit's thermal ceiling, switching frequency, and physical footprint.

The Core Physics: Bandgap and Breakdown Field

To understand what changes in a real circuit when you swap materials, you have to look at the atomic lattice. The defining metric here is the bandgap energy, measured in electron-volts (eV). Think of the bandgap as the minimum toll an electron must pay to cross from the valence band to the conduction band; a higher toll means the material won't accidentally leak current when it gets hot.

Silicon has a bandgap of 1.12 eV. Silicon Carbide has a bandgap of 3.26 eV. This nearly 3x difference in bandgap directly translates to a massive difference in the critical breakdown electric field. SiC can block roughly 10 times the voltage of Si for the exact same drift layer thickness. In a real installation, this means a 1200V SiC MOSFET has a much thinner, lower-resistance drift region than a 1200V Si IGBT, drastically reducing conduction losses and eliminating the minority-carrier tail current that plagues silicon switches during turn-off.

Worked Numeric Example: Conduction and Switching Losses

Let’s put numbers to the physics. Assume you are designing an 800V DC bus buck converter running at 20A continuous current and a 100 kHz switching frequency. We will compare a standard 1200V Silicon IGBT against a 1200V Silicon Carbide MOSFET.

Scenario A: 1200V Si IGBT

• Conduction Loss: A typical Si IGBT has a collector-emitter saturation voltage ($V_{CE(sat)}$) of about 1.7V at 20A.
  Power = $1.7V \times 20A = 34W$.
• Switching Loss: Due to the minority carrier tail current, turn-off energy ($E_{off}$) is high. Let's assume total switching energy ($E_{on} + E_{off}$) is 1.2 mJ per cycle.
  Power = $1.2 \times 10^{-3} J \times 100,000 Hz = 120W$.
• Total Dissipation: $34W + 120W = 154W$. This requires a massive, actively cooled extruded aluminum heatsink.

Scenario B: 1200V SiC MOSFET (e.g., 40mΩ RDS(on))

• Conduction Loss: SiC is a unipolar device with a resistive on-state. At 100°C junction temp, $R_{DS(on)}$ derates to roughly 60mΩ.
  Power = $I^2 \times R = 400 \times 0.06\Omega = 24W$.
• Switching Loss: With no tail current, switching is incredibly sharp. Total switching energy drops to about 0.15 mJ per cycle.
  Power = $0.15 \times 10^{-3} J \times 100,000 Hz = 15W$.
• Total Dissipation: $24W + 15W = 39W$. You can cool this with a small, passive stamped-metal fin array.

Where You Meet This in Practice

You are increasingly likely to encounter SiC in high-voltage, high-efficiency commercial and DIY-adjacent power systems:

• Solar String Inverters: Modern 1500V DC solar architectures rely entirely on SiC modules. The material's high thermal conductivity allows these inverters to sit on rooftops in 50°C ambient heat without derating their output.
• EV Traction Inverters: The shift to 800V battery architectures in electric vehicles (pioneered by the Porsche Taycan and Tesla Model 3 Plaid) is only possible because SiC MOSFETs minimize switching losses at those extreme voltages, directly adding 5-10% more range to the vehicle.
• Server Power Supplies: To achieve "Titanium" efficiency ratings (96%+ efficiency at 50% load) in data center power supplies, designers use a hybrid approach: GaN for the high-frequency LLC resonant stage, and SiC for the high-voltage PFC (Power Factor Correction) stage.

According to the U.S. Department of Energy, wide-bandgap semiconductors like SiC can reduce power conversion losses by up to 90% compared to legacy silicon systems, which is why they are central to modern grid-tie and renewable energy infrastructure.

Common Confusions: Materials vs. Devices and the Germanium Myth

When discussing this on the bench, two major confusions constantly trip up hobbyists and junior engineers.

Confusion 1: Conflating the material with the device architecture.
Silicon Carbide is a material, not a device. You can build a MOSFET, a JFET, a Schottky diode, or a BJT out of SiC. However, because SiC has a native silicon dioxide ($SiO_2$) oxide layer just like standard silicon, the MOSFET architecture is the most commercially viable. When a datasheet from Infineon or Wolfspeed says "SiC," they usually mean a SiC MOSFET or a SiC Schottky diode, but you must verify the topology to understand the gate drive requirements.

Confusion 2: The "Germanium is still common" myth.
If you read older textbooks, they will list Silicon and Germanium as the two primary semiconductor materials. Germanium has a very low forward voltage drop (~0.3V compared to Silicon's ~0.7V), which made it ideal for early crystal radios and 1960s transistor circuits. However, Germanium's bandgap is only 0.67 eV. This means at around 85°C, thermal energy alone is enough to excite electrons across the gap, causing the device to lose its semiconducting properties and fail via thermal runaway. Germanium is effectively dead in power electronics; it survives only in niche audio distortion pedals and specialized RF detectors.