Current-Voltage Characteristics and Charge-Carrier Traps in N-Type 4H-SiC Schottky Structures

Because of their high switching speeds and low power losses, metal-SiC Schottky-barrier diodes (SBD) are important to high performance, high temperature, and high frequency applications in power electronics. The use of 4H-SiC in SBDs is particularly advantageous because it has higher electron mobility than other SiC polytypes. In this work we examine current-capacitance-voltage-temperature properties of Ti on 4H-SiC SBDs and develop fitting algorithms to extract diode parameters based on inhomogeneous barrier height analysis approaches. Also the quality of 4H-SiC is evaluated in terms of electrically active defects: this part of the work utilizes Fourier-transform deep level transient spectroscopy (FT-DLTS) to probe carrier traps. FT-DLTS reveals the presence of an electron trap located in energy at ~ 0.6 eV below the conduction band edge. This electron trap possesses a large capture cross section for electrons of the order of 10^-12 cm² which suggests that the electron capture is Coulombic and the associated charge transition in the defect is between positive and neutral states