MSc Shaogang Wang

1. Reverse Recovery Optimization of Multiepi Superjunction MOSFET Based on Tunable Doping Profile
   Ke Liu; Chunjian Tan; Shizhen Li; Wucheng Yuan; Xu Liu; Guoqi Zhang; Paddy French; Huaiyu Ye; Shaogang Wang;
   Electronics,
   Volume 12, Issue 2977, 2023. DOI: https://doi.org/10.3390/electronics12132977
   
   Keywords: ...

   superjunction; MOSFET; doping profile; reverse recovery; body diode.
   
   
   Abstract: ...

   This paper proposes and simulates research on the reverse recovery characteristics of two novel superjunction (SJ) MOSFETs by adjusting the doping profile. In the manufacturing process of the SJ MOSFET using multilayer epitaxial deposition (MED), the position and concentration of each Boron bubble can be adjusted by designing different doping profiles to adjust the resistance of the upper half P-pillar. A higher P-pillar resistance can slow down the sweep out speed of hole carriers when the body diode is turned off, thus resulting in a smoother reverse recovery current and reducing the current recovery rate (dir/dt) from a peak to zero. The simulation results show that the reverse recovery peak current (Irrm) of the two proposed devices decreased by 5% and 3%, respectively, compared to the conventional SJ. Additionally, the softness factor (S) increased by 64% and 55%, respectively. Furthermore, this study also demonstrates a trade-off relationship between static and reverse recovery characteristics with the adjustable doping profile, thus providing a guideline for actual application scenarios.

2. Rapid Fabrication of High-Performance Flexible Pressure Sensors Using Laser Pyrolysis Direct Writing
   Shaogang Wang; Qihang Zong; Huiru Yang; Chunjian Tan; Qianming Huang; Xu Liu; Guoqi Zhang; Paddy French; Huaiyu Ye;
   Applied Materials and Interfaces,
   2023. DOI: https://doi.org/10.1021/acsami.3c04290
   
   Keywords: ...

   flexible pressure sensor, UV laser, laser direct writing, continuous laser pyrolysis, PDMS, micro-truncated pyramid.
   
   
   Abstract: ...

   The fabrication of flexible pressure sensors with low cost, high scalability, and easy fabrication is an essential driving force in developing flexible electronics, especially for high-performance sensors that require precise surface microstructures. However, optimizing complex fabrication processes and expensive microfabrication methods remains a significant challenge. In this study, we introduce a laser pyrolysis direct writing technology that enables rapid and efficient fabrication of high-performance flexible pressure sensors with a microtruncated pyramid array. The pressure sensor demonstrates exceptional sensitivities, with the values of 3132.0, 322.5, and 27.8 kPa−1 in the pressure ranges of 0−0.5, 0.5−3.5, and 3.5−10 kPa, respectively. Furthermore, the sensor exhibits rapid response times (loading: 22 ms, unloading: 18 ms) and exceptional reliability, enduring over 3000 pressure loading and unloading cycles. Moreover, the pressure sensor can be easily integrated into a sensor array for spatial pressure distribution detection. The laser pyrolysis direct writing technology introduced in this study presents a highly efficient and promising approach to designing and fabricating high-performance flexible pressure sensors utilizing micro-structured polymer substrates.

3. Flexible and Highly Sensitive Pressure Sensor Based on Patterned PDMS Forming with Laser Pyrolysis Direct Write Technique for Wearable Electr
   Shaogang Wang; Qihang Zong; Chunjian Tan; Huaiyu Ye; Paddy French;
   In MNE 2022,
   September 2022.

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