What Substrates Are Used for Wide-Bandgap Semiconductors?  

university wafer substrates

Wafers Used for Wide-Bandgap Semiconductors

A PhD in physics requested a quote for the following:

We need the followng substrate specs. We use the wafers as substrates for sample production of wide bandgap semiconductors doped with rare earths.

Al2O3 - Sapphire Wafer,
C-axis (0001), 10x10x1mm, DSP

CaF2 polished window
10*10+0/-0.1mm*1+/-0.1mm, DSP

Fused Silica JGS2
10x10+0/-0.1mmx1.0+/-0.1mm, DSP

Reference #58231 for specs and pricing.

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Wide Bandgap Semiconductor Crystal Lattice Structure SiC / GaN / Ga₂O₃ / Diamond Band Structure Conduction Band Wide Bandgap 3.0 - 6.0 eV Valence Band 6.0 eV 3.0 eV 1.1 eV 0 eV Si GaAs Key Properties & Applications Properties: • High breakdown field • High thermal conductivity • Low carrier generation • High temperature operation Applications: • Power electronics • High-frequency RF devices • Blue/UV LEDs & lasers • High temperature sensors Common Examples: SiC (3.3 eV), GaN (3.4 eV), Ga₂O₃ (4.9 eV), Diamond (5.5 eV), AlN (6.0 eV)

The image above shows the key characteristics of wide bandgap semiconductors, which are materials with significantly larger energy gaps between their valence and conduction bands compared to conventional semiconductors like silicon.

The diagram includes:

  1. Crystal Lattice Structure - A representation of a hexagonal crystal structure typical of wide bandgap semiconductors like Silicon Carbide (SiC) or Gallium Nitride (GaN).
  2. Band Structure - A visual of the energy band diagram showing:
    • The conduction band (top)
    • The wide bandgap region (middle) with energies typically between 3.0-6.0 eV
    • The valence band (bottom)
    • A comparison scale showing how the bandgap compares to conventional semiconductors like Silicon (1.1 eV) and Gallium Arsenide (1.4 eV)
  3. Key Properties:
    • High breakdown field
    • High thermal conductivity
    • Low carrier generation
    • High temperature operation capability
  4. Applications:
    • Power electronics
    • High-frequency RF devices
    • Blue/UV LEDs and lasers
    • High temperature sensors
  5. Common Examples of wide bandgap semiconductors with their bandgap energies:
    • Silicon Carbide (SiC): 3.3 eV
    • Gallium Nitride (GaN): 3.4 eV
    • Gallium Oxide (Ga₂O₃): 4.9 eV
    • Diamond: 5.5 eV
    • Aluminum Nitride (AlN): 6.0 eV

These materials are increasingly important in modern electronics because they can operate at higher temperatures, voltages, and frequencies than traditional semiconductors, enabling more efficient power conversion and more compact electronic devices.

What Are Wide-Bandgap Semiconductors? 

Wide-bandgap semiconductors (WBGs) are materials that have a larger bandgap compared to conventional semiconductors like Silicon (Si) or gallium arsenide (GaAs). The bandgap is the energy difference between the valence band (where electrons are bound to atoms) and the conduction band (where electrons are free to conduct electricity).

Key Features of Wide-Bandgap Semiconductors:

  1. Larger Bandgap: Typically greater than 2.2 electron volts (eV), compared to silicon’s bandgap of 1.12 eV.
  2. High Temperature Operation: Their large bandgap enables them to operate at much higher temperatures without significant leakage currents.
  3. High Breakdown Voltage: WBG materials can sustain much higher electric fields before breaking down, making them ideal for high-voltage applications.
  4. High Power Density: They can handle more power in a smaller volume compared to traditional semiconductors.
  5. High Switching Speeds: WBG devices can switch faster than silicon-based devices, making them efficient for high-frequency applications.
  6. High Thermal Conductivity: Materials like silicon carbide (SiC) and gallium nitride (GaN) have excellent thermal conductivity, aiding in efficient heat dissipation.

Wide bandgap semiconductor

Common Wide-Bandgap Materials:

  1. Silicon Carbide (SiC):
    • Bandgap: ~3.26 eV
    • Applications: Power electronics, high-voltage devices, electric vehicles, renewable energy systems.
  2. Gallium Nitride (GaN):
    • Bandgap: ~3.4 eV
    • Applications: High-frequency devices, RF amplifiers, LEDs, and laser diodes.
  3. Diamond:
    • Bandgap: ~5.5 eV
    • Applications: Niche high-power and high-temperature electronics.
  4. Aluminum Nitride (AlN):
    • Bandgap: ~6.2 eV
    • Applications: High-frequency devices, ultraviolet LEDs, and deep-UV lasers.

Applications of Wide-Bandgap Semiconductors:

  • Power Electronics: WBG devices like SiC MOSFETs and GaN HEMTs are used in electric vehicle chargers, power inverters, and renewable energy systems.
  • Telecommunications: GaN-based transistors are widely used in 5G and RF communication systems.
  • Lighting and Displays: LEDs made from GaN are efficient and widely used in general lighting, displays, and automotive headlights.
  • Aerospace and Defense: Their high-temperature and high-radiation tolerance make them suitable for satellites and military applications.
  • Medical Devices: WBG materials are used in lasers and imaging systems.

Wide-bandgap semiconductors are essential for advancing high-efficiency, high-power, and compact electronic systems in various industries.

UniversityWafer, Inc. offers deposition services for Wide Bandgap Ga2O3 films on substrates at 2” through 8” diameters or other shapes. Ga2O3 films have a Bandgap of ~4.9 eV and are of interest for UV sensors, buffer layers for nitrides, and as power devices, among other applications. Films deposited on Sapphire (0001) are crystalline as shown in the image. Films have also been grown on SiO2 layers on Si, as well as Si and quartz wafers. Deposition can be carried out on multiple 2”, 3” and 4” wafers as well as single 6” or 8” wafers. “As Grown” films are highly oriented and highly resistive. Doped films are also possible as a special order.

Ga2O3 Substrates for wide bandgap semiconductors

Ga2O3 on 2” Sapphire Wafer

Ga2O3 on 8” Si wafer
< 3% Std Dev

Product Specifications:
Direct Bandgap: ~4.9 eV
FWHM on sapphire: 0.65O @ ~400 on Sapphire
Thermal Stability: High
Transmission: High through UV
Sheet Resistance: Undoped - Highly Resistive
Adherence: High (Tape Test)
Thickness: 10-1000 nm (typically); 2” wafer ±5%
Area: Through 300 mm diameter substrates