GaN-on-GaN Collaboration for Efficient Light-Emitting Diodes
GaN-on-GaN has many advantages, such as vertical device structure, better heat dissipation, higher current density (5 x higher than sapphire), lower droop, lower crystal defects, etc that translate to higher efficiency devices. Our research focuses on epitaxy engineering to achieve ultimate device performance.
GaN-on-Si Collaboration for Cost-Efficient Power Devices
The development of high frequency AlGaN-based high electron mobility transistors (HEMT) is of great interest due to their promising applications in high-power switching and radio frequency operations. GaN-on-Si technology allows HEMTs mass-manufacturing on large-diameter Si wafers.
Non-Polar m-GaN & a-GaN
The performance of c-plane GaN has been shown to be limited by the piezoelectric polarization along the polar-axis of the quantum well. Therefore, numerous
efforts have been undertaken to grow GaN along non-polar directions such as non-polar m- and a-GaN. Our work employs 3-step growth technique to obtain m-GaN and a-GaN, with optimizations such as SLS or multi-layer to further enhance the crystal quality and surface morphology of the non-polar m- and a-GaN.
The majority of achievements in the field of III-nitride optoelectronics are mainly limited to polar GaN grown on c-plane (0001) sapphire. To date, it is still a great challenge to develop nitride-based longer wavelength devices such as green, yellow and red emitters. One clear way forward would be to grow III-nitride device structures along a semi-polar orientation, which potentially leads to both enhanced indium incorporation into GaN and reduced quantum confined Stark effects.
Why Nitride Semiconductors?
Group-III nitride semiconductors have been recognized as among the most promising materials for optical devices in the short-wavelength region because of their wide bandgap with direct transition. Since the AlGaInN system can cover a very wide wavelength range, from 200 nm to more than 1700 nm, it is applicable for optoelectronics devices in the ultra-violet (UV), visible and infra-red (IR) region. The high electron-saturation velocity in GaN is also suitable for application in high-speed and high-power electronic devices. The superior physical and chemical stability of the nitride semiconductors will enable them to operate in harsh environments. Moreover, nitride-based devices are the most “environmentally friendly” ones available.