Fabrication and characterization of fully implanted n(+)-p junction diode and metal semiconductor field effect transistor (MESFET) in 4H-silicon carbide

Silicon carbide (SiC) is a large bandgap semiconductor material which is receiving increasing attention in the past ten years for use in high power, high temperature, and high frequency electronic device applications. The very properties of SiC that make it an attractive semiconductor for electronic device applications also make it hard to process. Selective area doping by ion implantation is one of the most important processing steps that requires attention to advance SiC technology. This work is aimed at developing the ion-implantation doping technology in SiC and fabricating demonstrative devices using ion implantation.; In this work, n- and p-type ion-implantation doping technology in 4H-SiC is developed. Optimum post-implant annealing conditions are found for maximum activation of implanted dopant and removal of implant damage, while preserving material surface morphology. Ion implant distributions are modeled using empirical formulas for the four moments of the Pearson IV distribution function. Dopant electrical characteristics are assessed using capacitance-voltage and van der Pauw Hall measurements, post-implant substrate lattice quality by Rutherford Backscattering Spectroscopy, and surface morphology by Atomic Force Microscopy.; Selective-area, fully ion implanted n+-p junction diodes are fabricated in an n-type 4H-SiC epilayer using double specie implantations, and characterized for their current-voltage, capacitance-voltage, and transient switching traits. This device required a deep acceptor implant for the p-type region, followed by a shallow depth donor ion implantation for the n-type region. The diodes are tested over the temperature range 25–200°C. A study of these diodes gives insight into the fabrication of more complicated device structures, such as complementary field effect transistor devices or thyristors, that require combinations of multiple specie implants.; Metal semiconductor field effect transistors (MESFETs) were fabricated in semi-insulating bulk 4H-SiC by ion implantation of both the source/drain and the channel regions, using an aluminum Schottky gate metal and nickel ohmic contacts. Bulk mobility and channel mobility were determined. Devices were tested for their current voltage characteristics over the temperature range 25°C to 350°C.