Session Index

We developed III-nitride quantum dot (QD) uniform arrays using MOCVD, forming single InGaN QDs at the apex of six-fold and three-fold symmetric GaN pyramids via a selflimited growth mechanism. This method enables precise control of QD position, size, and symmetry, crucial for high-purity single-photon and polarization-entangled photon generation.
We also fabricated GaN hexagonal microrods and triangular prisms supporting whispering gallery and superscar modes, respectively, achieving room-temperature exciton-polariton condensation. These advances in QD symmetry control and microcavity engineering pave the way for integrated quantum photonic and polaritonic devices.


  Preview abstract

Gallium nitride (GaN) has become central to wide band gap power electronics, with decades of progress driving its adoption in sub-1kV applications and establishing it as a preferred choice for low-voltage systems. Silicon carbide (SiC) currently dominates the 1-3kV range, while gallium oxide (Ga2O3), with its ultra-wide band gap and higher breakdown strength, promises operation beyond both GaN and SiC. This raises a key question: which material will shape the future of high-voltage power electronics?
This talk will compare GaN, SiC and Ga2O3 across different voltage regimes, highlighting their performance advantages as well as key challenges in reliability, scalability and thermal management. Emphasis will be placed on high-voltage device architectures, defect-driven degradation, and emerging strategies such as heterogeneous integration, providing insights into pathways for next-generation, energy-efficient power conversion systems.

  Preview abstract

In this work, isolation techniques for AlGaN/GaN high electron mobility transistors (HEMTs) are systematically optimized. To enhance isolation and reduce damage from processes such as ICP-RIE etching, ohmic annealing is performed before ion implantation, followed by CF₄ surface treatment. The optimized devices exhibit a five-order-of-magnitude improvement in the On/Off current ratio, primarily driven by a substantial reduction in gate leakage current. These results indicate better channel control and effective leakage suppression, making this approach highly promising for high-power applications.

  Preview abstract

A GaN-based metalens collimator (MC) is designed to convert a light-emitting dipole
to a plane wave. Optical simulations predicted that the far-field divergence angle can be reduced
below 10̊ for the dipole emission of the focus. However, when random off-focus dipoles are
taken into account, the overall enhancement declines significantly. We fabricated MC mosaic
partitions of different widths on the backside of light-emitting diode (LED) epitaxy to optimize
the overall enhancement. Angle-resolved photoluminescence measurements showed that the
frontal luminance of micro-LED with a 4-μm MC mosaic was boosted by 2.84 times compared
to the reference sample without MC.

  Preview abstract

Thick semi-insulating gallium nitride layers doped with magnesium were fabricated on conductive ammonothermal gallium nitride substrates by magnesium ion implantation followed by ultra-high-pressure annealing at 1450 degrees Celsius for twenty-five hours under one gigapascal of nitrogen. Secondary ion mass spectrometry revealed “box-like” magnesium profiles with nearly constant concentration extending ten to twelve micrometres, enabling full compensation of silicon and oxygen donors. Covering the implanted surface reduced magnesium out-diffusion and increased penetration depth. Structural analyses confirmed preservation of crystalline quality and confinement of implantation-induced defects, providing a robust and cost-effective alternative to manganese-doped substrates for high-performance gallium nitride-based electronics.

  Preview abstract

This research investigates the performance improvement of blue QLEDs by
introducing ZnO nanoparticles (ZnO NPs) as a charge control layer (CCL) between stacked
quantum dot emissive layers. The incorporation of the CCL effectively enhances the device’s
brightness and efficiency, achieving a maximum luminance (Lmax) of 102,029 cd/m² and a peak
current efficiency (CEmax) of 3.13 cd/A. These results demonstrate the significant impact of
CCL integration on boosting blue QLED performance, particularly in terms of luminance
enhancement and charge balance optimization.

  Preview abstract

GaN-based laser diodes (LDs) are vital for next-generation displays and communications, yet achieving efficient long-wavelength operation remains challenging. We investigate InGaN quantum wells (QWs) of varying thickness and reveal that wide QWs enable lasing up to 20 nm longer than thin-QW counterparts of identical composition. Optical studies show that spontaneous emission originates from highly excited states, while population inversion and lasing occur only from lower excited states. This distinction between electroluminescence and optical gain overturns conventional assumptions and highlights wide-QW as a promising route toward long-wavelength LDs, if strain-related issues can be mitigated.

  Preview abstract