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In this paper, a 3D printing system for a thermal battery electrode ink film is set up and investigated based on the on-demand microdroplet ejection technology. The optimal structural dimensions of the spray chamber and metal membrane of the micronozzle are determined via simulation analysis. The workflow and functional requirements of the printing system are set up. The printing system includes a pretreatment system, piezoelectric micronozzle, motion control system, piezoelectric drive system, sealing system, and liquid conveying system. Different printing parameters are compared to obtain optimized printing parameters, which can be attributed to the optimal pattern of the film. The feasibility and controllability of 3D printing methods are verified by printing tests. The size and output speed of the droplets can be controlled by adjusting the amplitude and frequency of the driving waveform acting on the piezoelectric actuator. So, the required shape and thickness of the film can be achieved. An ink film in terms of nozzle diameter = 0.6 mm, printing height = 8 mm, wiring width = 1 mm, input voltage = 3 V and square wave signal frequency = 35 Hz can be achieved. The electrochemical performance of thin-film electrodes is crucial in thermal batteries. The voltage of the thermal battery reaches its peak and tends to flatten out at around 100 s when using this printed film. The electrical performance of the thermal batteries using the printed thin films is found to be stable. This stabilized voltage makes it applicable to thermal batteries.

The graded-channel high-electron-mobility transistors (HEMTs) with graded AlGaN buffer are investigated in this paper by Atlas drift-diffusion simulation. The short-channel effects (SCEs) are suppressed in a manner by employing the graded AlGaN buffer instead of the fixed Al-content AlGaN buffer. Then, the Al-content of the graded AlGaN channel is also optimized. The flatter and wider transconductance and current gain cutoff frequency (fT) curves are garnered by utilizing the graded AlGaN channel whose top Al-content is the same as the AlGaN barrier. At the gate length (LG) of 50 nm, the saturated drain current of the proposed device is 0.98 A/mm, which is 34% higher than the reference device. Simultaneously, the fT and fT×LG are also analyzed with the gate length from 50 nm to 250 nm. The fT of the proposed architecture is 181 GHz at LG = 50 nm and VGS = 1 V which is 12% higher than the reference device under the same conditions. The fT×LG is up to 19.2 GHz·μm at the gate length of 250 nm, and it obtains a 12% improvement over the reference device.