Search

Spatial nonuniformity of responsivity of 4H-SiC avalanche photodiodes at high gain is reported that results from variation in the doping density. Two-dimensional raster scans show a steady decline laterally across the device.

Temperature-dependent current-voltage (I-V) measurements are used to determine the reverse dark current mechanisms in 4H-SiC avalanche photodiodes (APDs). A pn junction vertical mesa structure, passivated with SiO2 grown by plasma enhanced chemical vapor deposition, exhibits predominate leakage current along the mesa sidewall.

Temperature-dependent current-voltage (I-V) measurements have been used to determine the reverse dark current mechanisms in 4H-SiC avalanche photodiodes (APDs). A pn junction vertical mesa structure, passivated with SiO2 grown by plasma enhanced chemical vapor deposition, exhibits predominate leakage current along the mesa sidewall. Similar APDS, passivated by thermal oxide, exhibit lower dark current before breakdown; however, when the temperature is higher than 146 ° C, an anomalous dark current, which increases rapidly with temperature, is observed. This current component appears to be eliminated by the removal of the thermal oxide. Near breakdown, tunneling is the dominant dark current mechanism for these pn devices. APDs fabricated from a pp-n structure show reduced tunneling current. At room temperature, the dark current at 95% of breakdown voltage is 140 fA (1.8 nA/cm²) for a 100-µm diameter APD. At a gain of 1000, the dark current is 35 pA (0.44 µA/cm²). [ABSTRACT FROM AUTHOR]

SiC bipolar devices are favored over SiC unipolar devices for applications requiring breakdown voltage in excess of 10 kV. We have designed and fabricated p-channel insulated-gate bipolar transistors (IGBTs) in 4H-SiC with 12-kV blocking volt- age for high-power applications. A differential on-resistance of 18.6 mΩ cm2 was achieved with a gate bias of 16 V, corresponding to a forward voltage drop of 5.3 V at 100 A/cm2, indicating strong conductivity modulation in the p-type drift region. A moderately doped current enhancement layer grown on the lightly doped drift layer effectively reduces the JFET resistance while maintaining a high carrier lifetime for conductivity modulation. The p-channel IGBT (p-IGBT) exhibits a transconductance that is 3 × higher than that of the 12-kV n-channel SiC IGBTs. An inductive switching test was done at 1.5 kV and 0.55 A (~140 A/cm2) for the p-IGBTs, and a turn-on time of 40 ns and a turn-off time of ~2.8 μs were measured. [ABSTRACT FROM AUTHOR]