A novel bi-piezoelectric jet dispenser with a zoom mechanism is proposed to distribute adhesives rapidly. The work frequency of the new jet dispenser can reach 500 Hz. The volume of the minimum dot is about 25 nL, and the volume error among dots is not more than ±10%. The dot size can be controlled by adjusting the driving voltage of the piezoelectric stack, filling pressure, and the opening time of the valve. Subsystem physical models of the jet valve are presented on the basis of the bi-piezoelectric principle and the zoom mechanism, which involves an electromechanical model, dynamic model, and fluid-solid coupling model. Based on these physical models, a coupled mechanical-electrical fluid simulation model is established, which can be simulated. The simulation results of the multiphysics-coupled model are in accordance with the experiment. The coupling model will develop a reliable simulating platform for high-speed fluid jet. The effectiveness of the bi-piezoelectric method and models is confirmed, and it will provide a new technology for microelectronics packaging.

To derive the impact of chip size reduction on optical efficiency in micro-LED array panels, blue InGaN/GaN LEDs, which consist of 21 × 7 arrays (60 ppi display) with different mesa sizes on sapphire substrates, are designed and fabricated in this study. Changing the mesa area of the chip is first proposed to investigate the luminous efficiency (cd/A) of the screen. The current efficiency with a peak wavelength of 450 nm reaches up to 14.29 cd/A for the biggest pixel 50 µ m × 60 µ m and to 12.25 cd/A for the 15 µ m × 25 µ m chip, delivering high-level efficiencies to the current LED research field. The mechanisms of size-dependent efficiency variation trends and efficiency droops of blue LEDs are investigated experimentally, confirming that the current efficiency is more efficient at high injection current density while exhibiting poorer performance at the low current density region for smaller chips. The peak efficiency corresponds to higher current density with a decrease in chip size according to the carrier recombination ABC model. Moreover, the characteristic curve of the spectrum and the changes in the yellow light band under different incident light conditions (i.e., 355 nm and 375 nm) are analyzed by photoluminescence.

Silicon Carbide (SiC) is a typical material for third-generation semiconductors. The thermal boundary resistance (TBR) of the 4H-SiC/SiO₂ interface was investigated by both experimental measurements and theoretical calculations. The structure of 4H-SiC/SiO₂ was characterized by using transmission electron microscopy and X-ray diffraction. The TBR was found to be 8.11 × 10⁻⁸ m²K/W at 298 K by the 3ω method. Furthermore, the diffuse mismatch model was employed to predict the TBR of different interfaces, which is in good agreement with measurements. Heat transport behavior based on the phonon scattering perspective was also discussed to understand the variations of TBR across different interfaces. Besides, the intrinsic thermal conductivity of SiO₂ thin films (200–1500 nm in thickness) on 4H-SiC substrates was measured by the 3ω procedure, to be 1.42 W/m K at 298 K. It is believed the presented results could provide useful insights into the thermal management and heat dissipation for SiC devices.