Nuclear Instruments and Methods in Physics Research A 367 (1995) 212-214 zyxwvutsrqponmlkjihgfedcbaZYXWV INSYRUMENYS ELSEVIER Silicon avalanche detectors with negative feedback high energy physics D. BiselloaVb, Yu. Gotra”‘“, V. Jejerc’*, V. Kushpil”, N. Malakhov”, Z. Sadygov”‘“, I. Stavitsky”, E. Tsyganovc9’ zyxwvutsrqponmlkjihgfedcbaZYXWVUT “INFN, Sezione di Padova, via Matzo10 8, 35131 Padova, Italy as detectors for A. Paccagnella”‘d, bDipartimento di Fisica, Universita di Padova, via Manolo 8, 35131 Padova, Italy ‘Laboratory of High Energy, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russian Federation dDipartimento di Elettronica e Informatica, Universita di Padova, via Gradenigo 6a, 3.5131 Padova, Italy ‘Physics Institute of Azerbaijan Academy of Sciences, Baku, Azerbaijan ‘Superconducting Super Collider Laboratory, Dallas. ‘IX 75273, USA zyxwvutsrqponmlkjihgfedcbaZYXW Abstract Some characteristics of silicon avalanche detectors with negative feedback based on the MRS (Metal-Resistive layer-Silicon) structure are presented. Special attention in this paper is paid to the temperature dependence of the detector characteristics. Possible applications in high energy physics experiments are also addressed. 1. Introduction Various semiconductor devices are used now for charged particle registration and localisation in nuclear and high energy physics experiments. In principle, avalanche photo- diodes could represent an appealing choice for particle tracking. However, conventional devices based on the p-i-n structure usually present such drawbacks as high working bias (hundreds of V), need for cooling systems, difficulty in produce large areas and multichannel elements with high gain, which strongly limit their use to a limited number of applications. Silicon avalanche detectors with negative feedback based on MRS (Metal-Resistive layer-Silicon) structures’ [l-5] can supply a feasible alternative skipping many of the disadvantages of conventional devices. MRS detectors can be operated at room temperature and at relatively low voltages (=4OV), offering a multiplication coefficient as high as 104-105, with a good time resolution (<6OOps) [6,7]. They are routinely produced on low-cost low-resis- tivity silicon substrates, where both detector and pre- amplifying electronics can be easily integrated, thus giving further advantages over the high-resistivity substrates used for Si microstrip detectors. In this paper we shall present some electrical charac- * Corresponding author. E-mail geger@sunhe.jinr.dubna.su ’ The detectors were designed by Z. Sadygov with financial support of the Institute for Nuclear Research of the Russian Academy of Sciences. teristics of the MRS detectors, considering in detail the multiplication coefficient and breakdown voltage, and their behaviour as a function of the ambient temperature. 2. Detector structure and principles of operation Detectors have been produced on low-resistivity (1 R cm) p-type silicon substrates and have a metal (film)- Sic (film)-Si (bulk) structure. Instead of SIC, amorphous silicon can be used as resistive layer. Al, Ti, or Ni can be deposited as front metal, depending on the experimental purposes. The detector operation is based on the local negative feedback principle. When a minimum ionizing particle crosses the Si substrate, it creates approximately 100 electron-hole pairs per pm along its track. The generated charge can be collected in a Si sensitive region spanning the space charge region plus a diffusion length, with a total length of about 20 p,m in the normal biasing condition. Due to the high electric field at the Si surface, in excess of 3 X lo5 V/cm, impact ionization occurs resulting in a multiplication coefficient up to 10”. During the avalanche process, collection of the electrons at the Si/SiC interface and redistribution of the electric field in the space charge region both take place, thus lowering the potential drop across the depletion region. Such a local negative feedback also decreases the influence of the structure nonunifor- mities and bias voltage instabilities on the amplification coefficient. 0168-9002/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-9002(95)00540-4