Electrical features of diamond sensors D. Drachenberg, E. Kouznetsova, W. Lange, W. Lohmann

Diamond samples Fraunhofer Institute (Freiburg) : – (12 x 12 mm) –300 and 200 um –Different surface treatments : #1 – substrate side polished; 300 um #2 – cut substrate; 200 um #3 – growth side polished; 300 um #4 – both sides polished; 300 um –Metallization: 10 nm Ti nm Au

Main characteristics – initial measurements I(V) curve – leakage current –two polarities Charge collection distance – before irradiation –Sr-source –two polarities

I(V) dependence Extremely low currents => –Shielding –N 2 atmosphere Diamond Keithley 487 HV N2N2

I(V) dependence Open circuit measurements :

I(V) dependence Usual I(V) curve: Non-ohmic curve:

I(V) dependence Time dependence :

I(V) dependence Reproducibility:

IV dependence Comparison : #300VR(300V)500VR(500V)-300 VR(-300V)-500VR(-500V) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+13

I(V) dependence : Current results: –Average resistance ~( ) Ohm (ohmic behavior) –Different I(V) behaviors were obtained even within groups of the same surface treatment –I(t) dependence shows polarization effects which correspond to the hysteresis of the I(V) curves Further steps: – long term measurements – under irradiation

Charge collection distance measurements for diamond sensors D. Drachenberg, E. Kouznetsova, W. Lange, W. Lohmann

CCD & Gate PA discr delay ADC Sr 90 PM1 PM2 diamond Scint. Not irradiated samples CCD = f(HV) Both polarities Q meas. = Q created x ccd / L

Simulations: Sr + diamond source Mylar window diamond scintillator

Spectra obtained – noise and Sr signal Sr noise

CCD - before irradiation (1)

CCD - before irradiation (2)

CCD - before irradiation SensorR(Average) ccd Up 500V ccd Up 800V ccd Down 500V ccd Down 800V E E E E E (700V) E E+1133 (400V) E E E (400 V) E E

Simulations: Am + diamond

CCD –  spectra

CCD : Current results: –Values of CCD before irradiation: ( ) um –Surface treatment has an influence on CCD –Good resistance doesn’t mean high CCD Further steps: –Measurements of CCD dependence on an irradiation dose –Surface test – measurements with an  -source (~ 10 um of penetration) –Homogeneity over the area – with a narrow collimated Sr