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Pinhole Studies (not final). Creation of defined number of pinholes per chip Increase of leakage current according to LHC years also defines the voltage over the dielectric (with Rpoly= 1.8MOhm) Effect of pinholes on readout Gain vs. number of pinholes??
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Pinhole Studies (not final) • Creation of defined number of pinholes per chip • Increase of leakage current according to LHC years also defines the voltage over the dielectric (with Rpoly= 1.8MOhm) • Effect of pinholes on readout • Gain vs. number of pinholes?? • Gain vs. leakage current (= years of LHC operation) • Conclusion Preliminary F. Hartmann IEKP - Universität Karlsruhe (TH) IEKP - Universität Karlsruhe (TH)
Power Consumption P ~ UFD I ~ d2 d ~d3 60mA/cm3 Ileak(-10°C)= 270mA (W6b)540µA (module) P(500V, -10°C)=135mW/sensor IEKP - Universität Karlsruhe (TH)
bond Al AC SiO2 P+ DC Setup Array of IR LED for cont. illumination increase in total current with standard reverse bias. Bonding artificial pinholes on purpose! • Ichannel=Itot / #channel=Itot/1024 • Vdrop=Istrip*Rpoly = Istrip*1.8MOhm • 300µA/1024 *1.8MOhm= 0.5V • 30µA=0.05V • ... IEKP - Universität Karlsruhe (TH)
Noise vs. leakage current Vb=500V; Il=0.3µA Vb=500V; Il=30µA Vb=500V; Il=300µA • Pinholes highly leakage current dependent • Very difficult to tag at starting current level IEKP - Universität Karlsruhe (TH)
Pedestals vs. leakage current NO change Vb=500V; Il0.3µA Vb=500V; Il 30µA Vb=500V; Il 120µA Vb=500V; Il 300µA IEKP - Universität Karlsruhe (TH)
Gain vs. leakage current (calibration) (Vbias=500V) (5&6 pinholes) Il 0,3µA ph 330 Il 30µA (Vdrop=0.05V) ph 300 p Preliminary p Il 60µA ph 280 Il 90µA ph 260 p p p p IEKP - Universität Karlsruhe (TH)
Gain vs. leakage current (calibration) (Vbias=500V) (5&6 pinholes) Il 150µA ph 255 Il 240µAph 255 Preliminary Il 300µA (0.5V) ph 255 No change in gain at leakage currents above 150µA (up to 300µA) ?? IEKP - Universität Karlsruhe (TH)
Calibration/Gain Vbias=500V; Il 60µA (Vdrop=0.1V) No pinholes 3 pinholes 4 pinholes p p IEKP - Universität Karlsruhe (TH)
Common mode 0 pinholes Vbias = 400V Il = 200µA 10 pinholes IEKP - Universität Karlsruhe (TH)
Conclusion • We bonded up to 10 pinholes per chip and imposed a current of 300µA/modules (330nA/channel; Vdrop = 0.5V) ~ 5 years of LHC operaton. • No saturation of chip seen; but final current level not yet reached. Only 300µA instead of 500-600µA • Gain loss and change in common mode with increasing leakage current and number of pinholes • Pinholes easy to tag with high current. IEKP - Universität Karlsruhe (TH)
IV-Curve before/after Irrad. IEKP - Universität Karlsruhe (TH)