& *H zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA __ l!iB __ ELSEVIER Nuclear Instruments and Methods in Physics Research A 362 (1995) 315-337 NUCLEAR INSTRUMENTS (LMEmoDS IN PHYSICS RESEARCH Sectlor A Characterization procedures for double-sided silicon microstrip detectors N.L. Bruner *, M.A. Frautschi, M.R. Hoeferkamp, S.C. Seidel zyxwvutsrqponmlkjihgfedcbaZ The New Mexico Center for Particle Physics, Uniuersity of New Mexico, Albuquerque, NM 87131, USA Received 23 January 1995 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Abstract Since double-sided silicon microstrip detectors are still evolving technologically and are not yet commercially available, they require extensive electrical evaluation by the user to ensure they were manufactured to specifications. In addition, measurements must be performed to determine detector operating conditions. Procedures for measuring the following quantities are described: - Leakage current, - Depletion voltage, - Bias resistance, - Interstrip resistance, - Coupling capacitance, - Coupling capacitor breakdown voltage. 1. Introduction Since double-sided silicon microstrip detectors are still evolving technologically and are not yet commercially available, they require extensive electrical evaluation by the user to ensure they were manufactured to specifica- tions. In addition, measurements must be performed on each detector to determine the required operating condi- tions. One of these measurements, bulk capacitance versus applied bias voltage, determines the depletion voltage, which determines the operating voltage. Another measure- ment, leakage current versus applied voltage, checks the current levels for compliance with power requirements. Both measurements are useful in determining the extent of damage to the detectors after irradiation ‘. Some of the detector parameters that are specified to the manufacturer and must be monitored for compliance are - bias resistance, - coupling capacitance, - interstrip resistance, - coupling capacitor breakdown voltage. The definition and importance of each will be discussed in turn. Bias resistance: Bias resistance is the resistance be- tween the implant strips and the voltage source that biases the detector. This is not the effective resistance of the p+ and n+ implant strips themselves but an additional resis- tance, orders of magnitude greater than the implant strip resistance 2. This bias resistance may be achieved with implanted polycrystalline silicon, or polysilicon. It is par- ticularly interesting because it is a relatively new technol- ogy and the measurements are needed to monitor the manufacturer’s consistency. It is significant because it acts as a current limiter which provides some measure of protection against shorts in the detector. Coupling capacitance: For the SVX II detectors, those p+ and ni ’ implant strips that are read out will be capaci- tively coupled to aluminum readout strips that lie directly over them. These aluminum readout strips are referred to as AC strips. The capacitance between each implant strip and its respective aluminum readout strip is called cou- pling capacitance. This coupling isolates the electronics from damaging bias voltage and current levels. It should be maximized to reduce the effects of parasitics, namely the interstrip and bulk capacitances. * Corresponding author. Tel. + 1 505 277 2616, fax + 1 505 2 Typical implant strip resistance is 90 k 0 /cm while specified 277 1520, e-mail bnmer@hepvl.phys.unm.edu. bias resistance for SVX II is 2 f 1 Ma. The SVX II detector is an ’ Further information on radiation damage may be found in upgrade in development for CDF at the Fermi National Accelera- Ref. [l-3]. tar Laboratory. 016%9002/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 016%9002(95)00280-4