What is GaN?
Gallium Nitride (GaN) is probably the most important semiconductor material since Silicon (Si). Its wide band gap of 3.4 eV along with the latest advancements in GaN substrate manufacturing technology make it viable for a variety of applications; namely, Ultra High Brightness (UHB) Light Emitting Diodes (LED), Laser Diodes (LD), and Power Electronic (high-power and high-frequency) devices. GaN based devices and end products offer a wide variety of compelling advantages and superior performance characteristics over the incumbent options. Learn more »
Because its wide band gap covers the solar spectrum from 0.65 eV to 3.4 eV (which is practically the entire solar spectrum), indium gallium nitride (InGaN) alloys are perfect for creating solar cell material. Because of this advantage, InGaN solar cells grown on GaN substrates are poised to become one of the most important new applications and growth market for GaN substrate wafers. Because of its low sensitivity to ionizing radiation (like other group III nitrides), it is also a suitable material for spaceborne applications such as solar cell arrays for satellites and high-power and high-frequency devices for communication, weather, and surveillance satellites.
GaN for semiconductor light
The main market driver for the use of GaN for the SSL applications like UHB-LEDs is dependent on improving the Internal Quantum Efficiency (IQE) of the device. Crystal orientation of the GaN substrate plays a major role in determining the IQE of the device. Currently, there are two commonly known and unsolved obstacles with the current SSL technologies in creating high-efficiency, high-brightness, and low cost SSL solutions. The first obstacle is the "droop", which is the subsequent leveling off or drop of LED efficiencies as the operating current increases, resulting in diminishing returns. The second obstacle is the "green gap", which is the decrease in efficiency as wavelengths shorten and move towards the green. Ostendo's GaN offering and product roadmap will help address both of these issues for UHB-LEDs to enable the higher-efficiency SSL devices.
The semi-polar advantage.
Why semi-polar?
Semi-polar materials have the GaN [0001] crystal direction neither normal nor parallel to the surface plane of the growth substrate. This orientation reduces deleterious polarization effects and allows for more efficient devices.
More light per dollar.
Conventional polar nitride optoelectronic devices suffer from deleterious polarization effects. By adjusting the crystal orientation, semi-polar materials significantly reduce these polarization effects and greatly improve efficiency.
Larger wafers.
Ostendo's proprietary semi-polar fabrication technology allows us to produce semi-polar GaN wafers that are 2", and soon 4" and 6".
Reduced internal polarization & piezo-fields.
- Higher injection efficiency
- Higher radiative recombination efficiency in QWs
- Wider QWs can be used (longer wavelength and better optical mode confinement)
- LDs with Al-free claddings can be designed
Increased & improved indium incorporation.
- Longer wavelength emission
- Decrease in optical losses
- Higher modal gain
- Higher Internal Quantum Efficiency (IQE)