Electrical and ultraviolet characterization of 4H-SiC Schottky photodiodes.

Fabrication and electrical and optical characterization of 4H-SiC Schottky UV photodetectors with nickel silicide interdigitated contacts is reported. Dark capacitance and current measurements as a function of applied voltage over the temperature range 20 °C - 120 °C are presented. The results show consistent performance among devices. Their leakage current density, at the highest investigated temperature (120 °C), is in the range of nA/cm(2) at high internal electric field. Properties such as barrier height and ideality factor are also computed as a function of temperature. The responsivities of the diodes as functions of applied voltage were measured using a UV spectrophotometer in the wavelength range 200 nm - 380 nm and compared with theoretically calculated values. The devices had a mean peak responsivity of 0.093 A/W at 270 nm and -15 V reverse bias.

Note: Dead time causes and correction method for single photon avalanche diode devices.

Single photon avalanche diode (SPAD) is the new generation of Geiger-Muller (GM) detectors, developed with semiconductor technology, and able to detect single photons, mainly in visible range. In this work we study the signal generation process and the dead time (DT) mechanisms of the device under a constant light regime. According to our results, it is possible to discriminate low rate signals from afterpulse and noise production and, moreover, to overcome the saturation effect due to the dead time losses. Starting from hybrid DT model [S. H. Lee and R. P. Gardner, Appl. Radiat. Isot. 53, 731 (2000)] we have been able to evaluate the real amount of incident photon rate up to 10(7) cps using a passive quenched device with 0.97 mus total dead time. In this way the passive quenched SPAD achieves the same performance of the active quenched one showing that relatively complex data analysis and complex device implementation are comparable solutions for constant light measurement. We also analyze some effects, lacking in GM counter, which should be introduced in the analysis of semiconductor device, as afterpulse, reduced photon detection efficiency, and noise production.