We describe new SOI lateral power devices which have a trench oxide to improve the device performance. High voltage super-junction (SJ) SOI-LDMOSFETs have a trench oxide in the drift region. It allows to reduce the drift length without degrading the breakdown voltage. With the proposed device structure a reduction of the on-resistance of the n-drift layer can be achieved. The breakdown voltage and the specific on-resistance of the suggested devices as a function of the trench oxide depth, the p-column width, and the doping are studied. Shorted-anode lateral insulated-gate bipolar transistors (SA-LIGBTs) on SOI have a trench oxide at the drain/anode region. It suppresses effectively the snap-back voltage inherent in conventional SA-LIGBTs without increasing the anode length of the device. Using the two-dimensional numerical simulator Minimos-NT, we confirm that the drift length of the proposed SJ SOI-LDMOSFETs is reduced to 65% compared to conventional devices, and a weak negative differential resistance region is observed with the proposed SOI SA-LIGBT. (C) 2004 Elsevier Ltd. All rights reserved.