GaN-on-Si(111) N/P Ttype substrate Epitaxy 4inch 6inch 8inch for
LED or Power device
GaN-on-Si substrate abstract
GaN-on-Si (111) substrates are essential in high-performance
electronics and optoelectronics due to their wide bandgap, high
electron mobility, and thermal conductivity. These substrates
leverage silicon's cost-effectiveness and scalability, enabling
large-diameter wafers. However, challenges like lattice mismatch
and thermal expansion differences between GaN and Si (111) must be
addressed to reduce dislocation density and stress. Advanced
epitaxial growth techniques, such as MOCVD and HVPE, are employed
to optimize crystal quality. GaN-on-Si (111) substrates are widely
used in power electronics, RF devices, and LED technology, offering
a balance of performance, cost, and compatibility with existing
semiconductor manufacturing processes.
GaN-on-Si substrate properties
Gallium Nitride on Silicon (GaN-on-Si) is a substrate technology
that combines the properties of Gallium Nitride (GaN) with the
cost-effectiveness and scalability of Silicon (Si). GaN-on-Si
substrates are particularly popular in power electronics, RF
devices, and LEDs due to their unique properties. Below are some
key properties and advantages of GaN-on-Si substrates:
1. Lattice Mismatch
- GaN and Si have different lattice constants, leading to a significant lattice
mismatch (~17%). This mismatch can cause defects, such as
dislocations, in the GaN layer.
- To mitigate these defects, buffer layers are often used between GaN
and Si to gradually transition the lattice constant.
2. Thermal Conductivity
- GaN has high thermal conductivity, which allows for efficient heat
dissipation, making it suitable for high-power applications.
- Si also has decent thermal conductivity, but the difference in
thermal expansion coefficients between GaN and Si can lead to
stress and potential cracking in the GaN layer during cooling.
3. Cost and Scalability
- Silicon substrates are significantly cheaper and more widely available
than other alternatives like Sapphire or Silicon Carbide (SiC).
- Silicon wafers are available in larger sizes (up to 12 inches),
allowing for high-volume production and lower costs.
4. Electrical Properties
- GaN has a wide bandgap (3.4 eV) compared to silicon (1.1 eV), which
results in high breakdown voltage, high electron mobility, and low
conduction losses.
- These properties make GaN-on-Si substrates ideal for
high-frequency, high-power, and high-temperature applications.
5. Device Performance
- GaN-on-Si devices often exhibit excellent electron mobility and
high saturation velocity, leading to superior performance in RF and
microwave applications.
- GaN-on-Si is also used in LEDs, where the substrate's electrical
and thermal properties contribute to high efficiency and
brightness.
6. Mechanical Properties
- The mechanical properties of the substrate are crucial in device
fabrication. Silicon provides a rigid and stable substrate, but the
GaN layer's mechanical stress due to lattice mismatch and thermal
expansion differences needs careful management.
7. Challenges
- The primary challenges with GaN-on-Si substrates include managing
the high lattice and thermal expansion mismatches, which can lead
to cracking, bowing, or defect formation in the GaN layer.
- Advanced techniques such as buffer layers, engineered substrates,
and optimized growth processes are essential to overcome these
challenges.
8. Applications
- Power Electronics: GaN-on-Si is used in high-efficiency power converters, inverters,
and RF amplifiers.
- LEDs: GaN-on-Si substrates are used in LEDs for lighting and displays
due to their efficiency and brightness.
- RF and Microwave Devices: High-frequency performance makes GaN-on-Si ideal for RF
transistors and amplifiers in wireless communication systems.
GaN-on-Si substrates offer a cost-effective solution for
integrating the high-performance properties of GaN with the
large-scale manufacturability of silicon, making them a critical
technology in various advanced electronic applications.
| Parameter Category | Parameter | Value/Range | Remarks |
|---|
| Material Properties | Bandgap of GaN | 3.4 eV | Wide bandgap semiconductor, suitable for high-temperature,
high-voltage, and high-frequency applications |
| Bandgap of Si | 1.12 eV | Silicon as a substrate material offers good cost-effectiveness |
| Thermal Conductivity | 130-170 W/m·K | Thermal conductivity of GaN layer; silicon substrate is
approximately 149 W/m·K |
| Electron Mobility | 1000-2000 cm²/V·s | Electron mobility in the GaN layer, higher than in silicon |
| Dielectric Constant | 9.5 (GaN), 11.9 (Si) | Dielectric constants of GaN and Si |
| Thermal Expansion Coefficient | 5.6 ppm/°C (GaN), 2.6 ppm/°C (Si) | Mismatch in thermal expansion coefficients of GaN and Si,
potentially causing stress |
| Lattice Constant | 3.189 Å (GaN), 5.431 Å (Si) | Lattice constant mismatch between GaN and Si, potentially leading
to dislocations |
| Dislocation Density | 10⁸-10⁹ cm⁻² | Typical dislocation density in the GaN layer, depending on
epitaxial growth process |
| Mechanical Hardness | 9 Mohs | Mechanical hardness of GaN, providing wear resistance and
durability |
| Wafer Specifications | Wafer Diameter | 2-inch, 4-inch, 6-inch, 8-inch | Common sizes for GaN on Si wafers |
| GaN Layer Thickness | 1-10 µm | Depending on specific application needs |
| Substrate Thickness | 500-725 µm | Typical thickness of the silicon substrate for mechanical strength |
| Surface Roughness | < 1 nm RMS | Surface roughness after polishing, ensuring high-quality epitaxial
growth |
| Step Height | < 2 nm | Step height in the GaN layer, affecting device performance |
| Wafer Bow | < 50 µm | Wafer bow, influencing process compatibility |
| Electrical Properties | Electron Concentration | 10¹⁶-10¹⁹ cm⁻³ | n-type or p-type doping concentration in the GaN layer |
| Resistivity | 10⁻³-10⁻² Ω·cm | Typical resistivity of the GaN layer |
| Breakdown Electric Field | 3 MV/cm | High breakdown field strength in the GaN layer, suitable for
high-voltage devices |
| Optical Properties | Emission Wavelength | 365-405 nm (UV/Blue) | Emission wavelength of GaN material, used in LEDs and lasers |
| Absorption Coefficient | ~10⁴ cm⁻¹ | Absorption coefficient of GaN in the visible light range |
| Thermal Properties | Thermal Conductivity | 130-170 W/m·K | Thermal conductivity of GaN layer; silicon substrate is
approximately 149 W/m·K |
| Thermal Expansion Coefficient | 5.6 ppm/°C (GaN), 2.6 ppm/°C (Si) | Mismatch in thermal expansion coefficients of GaN and Si,
potentially causing stress |
| Chemical Properties | Chemical Stability | High | GaN has good corrosion resistance, suitable for harsh environments |
| Surface Treatment | Dust-free, contamination-free | Cleanliness requirement for the GaN wafer surface |
| Mechanical Properties | Mechanical Hardness | 9 Mohs | Mechanical hardness of GaN, providing wear resistance and
durability |
| Young's Modulus | 350 GPa (GaN), 130 GPa (Si) | Young's modulus of GaN and Si, affecting the mechanical properties
of the device |
| Production Parameters | Epitaxial Growth Method | MOCVD, HVPE, MBE | Common epitaxial growth methods for GaN layers |
| Yield Rate | Depends on process control and wafer size | Yield is influenced by factors such as dislocation density and
wafer bow |
| Growth Temperature | 1000-1200°C | Typical temperature for GaN layer epitaxial growth |
| Cooling Rate | Controlled cooling | Cooling rate is usually controlled to prevent thermal stress and
wafer bow |
GaN-on-Si substrate real photo
GaN-on-Si substrate application
GaN-on-Si substrates are primarily used in several key
applications:
Power Electronics: GaN-on-Si is widely used in power transistors and converters due
to its high efficiency, fast switching speeds, and ability to
operate at high temperatures, making it ideal for power supplies,
electric vehicles, and renewable energy systems.
RF Devices: GaN-on-Si substrates are employed in RF amplifiers and microwave
transistors, particularly in 5G communications and radar systems,
where high power and frequency performance are crucial.
LED Technology: GaN-on-Si is used in the production of LEDs, especially for blue
and white LEDs, offering cost-effective and scalable manufacturing
solutions for lighting and displays.
Photodetectors and Sensors: GaN-on-Si is also utilized in UV photodetectors and various
sensors, benefiting from GaN’s wide bandgap and high sensitivity to
UV light.
These applications highlight the versatility and importance of
GaN-on-Si substrates in modern electronics and optoelectronics.
Q&A
Q:Why GaN over si?
A:GaN on Si offers a cost-effective solution for high-performance
electronics, combining the advantages of GaN's wide bandgap, high
electron mobility, and thermal conductivity with the scalability
and affordability of silicon substrates. GaN is ideal for
high-frequency, high-voltage, and high-temperature applications,
making it a superior choice for power electronics, RF devices, and
LEDs. Silicon substrates enable larger wafer sizes, reducing
production costs and facilitating integration with existing
semiconductor manufacturing processes. Although there are
challenges like lattice mismatch and thermal expansion differences,
advanced techniques help mitigate these issues, making GaN on Si a
compelling option for modern electronic and optoelectronic
applications.
Q:What is GaN-on-Si?
A:GaN-on-Si refers to gallium nitride (GaN) layers grown on a
silicon (Si) substrate. GaN is a wide bandgap semiconductor known
for its high electron mobility, thermal conductivity, and ability
to operate at high voltages and temperatures. When grown on
silicon, it combines the advanced properties of GaN with the
cost-effectiveness and scalability of silicon. This makes GaN-on-Si
ideal for applications in power electronics, RF devices, LEDs, and
other high-performance electronic and optoelectronic devices. The
integration with silicon allows for larger wafer sizes and
compatibility with existing semiconductor manufacturing processes,
although challenges like lattice mismatch need to be managed.
