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This study examines the performance of SiC Schottky diodes with varied proton and Li microbeam energies, revealing improved properties such as high resistance to radiation damage and electrical homogeneity. However, challenges include thin depletion layers and defects at interface, affecting hole diffusion and carrier lifetime. The research also addresses the drawbacks of contacts technology and surface treatments in 4H-SiC material.
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IBICC ANALYSIS OF SiC SCHOTTKY DIODES • C. Manfredotti1, E. Vittone1, A. Lo Giudice1, C. Paolini1, F. Fizzotti1, F.Nava2 • 1Dip. Fisica Sperim., Università di Torino, INFM- Unità di Torino Università, via P.Giuria 1, 10125 Torino (I) • 2 Dipartimento di Fisica, Universitá di Modena, Via Campi 213/A, 41100 Modena, Italy
Summary • Review of previous measurements with 2 MeV protons • Preliminary results with Li and proton microbeams with energies from 0.7 to 1.7 MeV: new determination of hole diffusion length • Results with 3 keV x-ray microbeam at ESRF
SiC as a nuclear particle detector and X-ray spectrometer : • high resistance to radiation damage • larger band gap ( 3.3 eV ) and very low dark current • higher carrier saturation velocity ( 2 x GaAs ) • higher breakdown electrical field ( 0.3 MV/cm ) • large thermal conductivity • satisfactory electrical homogeneity • Problems and drawbacks : • thin depletion layer widths • defects at the interface of epilayers • contacts technology and surface treatments • pair creation energy not well known
4H-SiC from CREE Research; contacts from ALENIA Nominal active layer doping concentration: (Nd-Na)=2.2x1015 cm-3
Charge collection efficiency protons on SiC
The ID21 scanning X-ray microscope (SXM) ESRF -Grenoble 3 keV x-ray
X-ray microbeam at ESRF - Grenoble • spot size < 100 nm • 3 KeV X-ray energy : attenuation depth in SiC 4 mm • Au contact ( 100 nm thick ) attenuation 33 % • Measurement details : • photocurrent : Keithley 617 electrometer with output coupled to a voltage-to-frequency converter • pulse counting in a 100 ms time window ( 1 pulse = 2 pA ) • bias voltage 50 V • “ photocurrent spectra “ plotted in the same way as X-ray multichannel spectra obtained in pulse mode
Conclusions : • SiC epilayers electrically very homogeneous • electrical homogeneity increases with bias voltage • probable presence of extended electrical defects both at the surface and at the interface of the epilayer • first direct evaluation of hole diffusion length by variable energy frontal IBICC • hole diffusion length in a SiC n-epilayer, 2.2x1015 cm-3 net doping, evaluated as 8.5 um ; hole lifetime calculated as 0.24 ms