A novel lateral double-diffused MOSFET with multi-ring substrate (M-R LDMOS) is proposed. New high electric field peaks are introduced by the M-R due to the effect of the electric field modulation, which makes the lateral and vertical electric field distributions more uniform at the same time. As a consequence, the breakdown voltage (BV) of M-R LDMOS is enhanced significantly. The simulation result shows that the BV of M-R LDMOS is 566 V with the drift region length of $30~\mu \text{m}$ . Furthermore, the figure-of-merit of M-R LDMOS is 3.05 MW/cm ² , increased by 190%, 45%, and 24.5% in comparison with the conventional LDMOS, the step doping drift LDMOS, and the assisted deplete-substrate layer LDMOS, respectively. M-R LDMOS has a much better performance. In addition, the proposed M-R LDMOS uses the highly doped substrate ( $3\times 10^{15}$ cm ⁻³ ), which significantly reduces the cost of substrate.

A depletion-mode AlGaN/GaN high electron mobility transistors (HEMTs) have been proposed in this article with the partial GaN cap, which applies the electric field modulation effect to optimize the surface electric field and two-dimensional electron gas (2DEG) distribution. The 2DEG density under the partial GaN cap is reduced due to the polarization effect formed by the partial GaN cap and AlGaN layers. The surface electric field is reshaped by the electric field modulation effect due to the partial GaN cap, featuring an extra electric field peak far away from the gate edge, which, therefore, improves the breakdown voltage (BV). Moreover, the output current ( I _DS ) is also improved slightly resulting from the increased mobility of 2DEG, which compensates for the decrease in the 2DEG density. The experimental BV is increased greatly from 378 V for the conventional AlGaN/GaN HEMTs to 656 V for the depletion-mode partial cap layer AlGaN/GaN HEMTs because of the optimized surface electric field by the electric field modulation effect. The maximum output current ( I _max ) is increased from 538 to 558 mA/mm. It is concluded that the BV can be improved significantly and I _DS increased slightly for AlGaN/GaN HEMTs by the electric field modulation technique using the partial GaN cap, which optimizes the BV and specific ON-resistance ( R _ON,sp ) simultaneously.

A novel fast-switching silicon-on-insulator lateral insulated gate bipolar transistor (SOI LIGBT) is proposed and investigated in this article. The proposed device introduces trench barriers (TBs) at the collector end based on shorted anode (SA) structure to eliminate the snapback effect. The introduced TB structure can make the flow path of electron current be compressed and extended when the SA LIGBT is turned on so that the opening of collector p+/n-junction is prior to that of collector n+/n-junction. At the same time, it retains the ability to extract unbalanced electrons when the SA LIGBT is turned off. Through the TCAD simulation, the obtained results show that snapback-free can be realized by changing trench depth and pitch between TB structures. Compared with the separated SA (SSA) LIGBT, the forward voltage drop of the proposed LIGBT is reduced by 13.9% with snapback-free and much shorter collector region, which also retains the ability to extract unbalanced electrons. Thus, under the same forward voltage drop of 1.49 V, the turn-off time, and loss of the proposed LIGBT is 20.3% and 21.1% lower than those of the conventional (Conv.) LIGBT, respectively. In general, the tradeoff between turn-off time and forward voltage drop of the proposed LIGBT has much better performance.

In this paper, a novel snapback-free LIGBT with fast-switching and improved latch-up immunity is proposed and investigated by TCAD simulation. The structure features a shorted-anode NPN (SA NPN) beside the insulated oxide trench in the N-buffer and a lowly-doped P-region (PD) alongside the deep-oxide trench (DOT) in the N-drift. The SA NPN provides an effective path of electron extraction and completely suppresses the snapback voltage. The PD changes the transmission path of hole current, makes the distribution of hole current more uniform, and contributes to the depletion of the drift region. As simulation results show, at the same forward voltage drop of 1.40V, the turn-off time for the proposed SAPD LIGBT is reduced by 36.6% and 57.4%, respectively, compared with SA LIGBT and DOT LIGBT. In addition, compared to DOT LIGBT, breakdown voltage is increased by 7.6% and latch-up voltage is increased by nearly 20% for the proposed SAPD LIGBT.