In this paper, the device-partition method (DPM) is proposed to improve the efficiency in 3-D device simulation. The idea of DPM is that a device is divided into several parts, and, therefore, the matrix solver only solves a part of the device at a time. In order to obtain the accurate solution, the iteration method is necessary in DPM. By the continuous iteration, we can obtain the accurate simulation results. PN diode and MOSFET are demonstrated using DPM in this paper. The comparison of simulation results between our simulator and 3-D Davinci device simulator is presented. The consumption of CPU time and memory is also discussed in this paper. (c) 2006 Elsevier Ltd. All rights reserved.