Electrical properties of ion-implanted p-n junction diodes in β-SiC

Abstract

Mesa structure junction diodes prepared via high‐temperature ion implantation of Al+ (100 keV, 4.8×101 4 Al/cm2) in n‐type or N+ (90 and 180 keV, 0.9 and 1.3×101 4 N/cm2) in p‐type β‐SiC thin films were electrically characterized as a function of temperature using current‐voltage and capacitance‐voltage measurements. In either case, rectification was observed to the highest measurementtemperature of 673 K. Closer examination of the device current‐voltage characteristics yielded diode ideality factors greater than 2. Additionally, the log dependence of these two parameters indicated space‐charge‐limited current in the presence of traps as the dominant conduction mechanism. From the temperature dependence of log‐log plots, trap energies and densities were determined. Two trapping levels were observed: (1) 0.22 eV with a density of 2×101 8 cm− 3 and (2) 0.55 eV with a density of 2×101 6 cm− 3. The former is believed to be ionized Al centers (in the case of Al‐implanted sample) and the latter a compensating acceptor level, both of which lie within the bottom third of the band gap. Reverse currents at low biases were characteristic of generation in the depletion region. At intermediate biases an ohmic dependence was observed, whereas at high biases the current appeared to be space‐charge limited. Capacitance‐voltage measurements indicated both types of diodes were abrupt junctions.