IBICC ANALYSIS OF Si C SCHOTTKY DIODES C

IBICC ANALYSIS OF Si. C SCHOTTKY DIODES C. Manfredotti 1, E. Vittone 1, A. Lo Giudice 1, C. Paolini 1, F. Fizzotti 1, F. Nava 2 1 Dip. 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 C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 1

Summary > Review of previous measurements with 2 Me. V protons > Preliminary results with Li and proton microbeams with energies from 0. 7 to 1. 7 Me. V: new determination of hole diffusion length >Results with 3 ke. V x-ray microbeam at ESRF C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 2

Si. C as a nuclear particle detector and X-ray spectrometer : • high resistance to radiation damage • larger band gap ( 3. 3 e. V ) and very low dark current • higher carrier saturation velocity ( 2 x Ga. As ) • 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 C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 3

4 H-Si. C from CREE Research; contacts from ALENIA Nominal active layer doping concentration: (Nd-Na)=2. 2 x 1015 cm-3 C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 4

IBICC Set up C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 5

Proton energy 2 Me. V C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 6

2 Me. V Li C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 7

IBIC maps: protons on Si. C C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 8

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Charge collection efficiency protons on Si. C C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 10

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The ID 21 scanning X-ray microscope (SXM) ESRF -Grenoble 3 ke. V x-ray C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 12

C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 13

X-ray microbeam at ESRF - Grenoble • spot size < 100 nm • 3 Ke. V X-ray energy : attenuation depth in Si. C 4 mm • Au contact ( 100 nm thick ) attenuation 33 % Measurement details : • photocurrent : Keithley 617 electrometer with output coupled to a voltage-tofrequency converter • pulse counting in a 100 ms time window ( 1 pulse = 2 p. A ) • bias voltage 50 V • “ photocurrent spectra “ plotted in the same way as X-ray multichannel spectra obtained in pulse mode C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 14

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C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 16

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C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 19

Conclusions : • Si. C 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 Si. C n-epilayer, 2. 2 x 1015 cm-3 net doping, evaluated as 8. 5 um ; hole lifetime calculated as 0. 24 ms C. Manfredotti, Quartu S. Elena, 27 -30. 5. 2001 WOCSDICE 2001 Si. C 20