Design and fabrication of a low noise avalanche mode detector for future high-energy particle time-of-flight measurement

Sunhom Paak, Purdue University

Abstract

Future experiments in nuclear and high energy physics will require high pixel-density detector systems which are able to measure Time Of Flight (TOF) of fast charged particles with sub-100 ps precision. Conventional systems made of scintillators and fast photomultiplier tubes often cannot meet these requirements. As a new approach to TOF technology, a Gallium doped deep diffusion AValanche PIN Diode (AVD) has been designed and fabricated for direct detection of high energy Minimum Ionizing Particles (MIPs). Gallium diffusion makes a relatively deeper diffused junction of p − − n– and uniform depletion width. Using deep diffusion technique, a relatively wide peak electric field is made along the p− − n− junction and had much less hole multiplication than electron multiplication at a lower operating electric field of 1−2 × 105V/cm with k = ∼0.01. The dark current density of the AVD near edge of the breakdown voltage of 300V was 0.33$μA/cm 2 compared to a commercial EG&G diode (2μA/ cm2). An excess noise factor of 2.4 and a signal to noise ratio of about 1000 were measured at the gain of 50. The noise current of the Gallium doped deep diffusion AVD was 3.35 × 10−18 A2, which is 2.5 times less than the commercial EG&G AVD(8.24 × 10−18A 2) at the same gain of 50. The time resolution of the detecting system was measured at 62 ps with β− electrons of 3.5 MeV at a dose of 100 μCu with 106Ru (106Rh) as a source. The detecting resolution is two or three times better than a conventional high energy particle detector. A beveled angle (54.7°) side wall allowed lower edge leakage currents and permitted the fabrication of an array structure which could cover large areas.

Degree

Ph.D.

Advisors

Neudeck, Purdue University.

Subject Area

Electrical engineering

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