Optimum Barrier Height for SiC Schottky Barrier Diode

The study of barrier height control and optimization for Schottky barrier diode (SBD) from its physical parameters have been introduced using particle swarm optimization (PSO) algorithm. SBD is the rectifying barrier for electrical conduction across the metal semiconductor (MS) junction and, therefore, is of vital importance to the successful operation of any semiconductor device. 4H-SiC is used as a semiconductor material for its good electrical characteristics with high-power semiconductor devices applications. Six physical parameters are considered during the optimization process, that is, device metal, mobile charge density, fixed oxide charge density, interface trapped charge density, oxide thickness, and voltage drop across the metal-semiconductor contact. The optimization process was performed using a MATLAB program. The results show that the SBD barrier height has been optimized to achieve a maximum or minimum barrier height across the contact, in addition to the ability of controlling the physical parameters to adjust the device barrier height. 1. Introduction The successful operation of any semiconductor device is of vital importance. The barrier height reflects the mismatch in the energy position of semiconductor majority carrier band edge and the metal Fermi level across the MS interface. The ability to control the magnitude of this barrier height is crucial for the advancement of future electronic devices to higher functionality and smaller physical dimensions. Several researches in the literature studied the barrier height control during manufacturing process [1–5]. SiC material offers superior material properties such as large breakdown electric field, large band gap, high electron saturated velocity, and high thermal conductivity. This makes it a viable semiconductor for high-voltage application and high-temperature operation with reduced power loss. 4H-SiC is used for its advantage with high-power applications [6–8]. This paper proposes an optimization technique for controlling and optimizing the SBD barrier height to achieve the required device physical parameters during the design time. 2. Theoretical Description The structure of Schottky barrier diode (SBD) is illustrated schematically in Figure 1. In SiC, the device regions, where electrons and holes behave as bulk carriers, the Poisson equation can be described as follows [9]: where and are the densities of holes and electrons and , are the densities of ionized donors and acceptors; the holes and electrons densities are [9] The electric field at the surface is The space charge per