Designs and electric properties studied of 3D trench electrode Si detector with adjustable central collection electrode

Chuan Liao,Jun Zhao,Manwen Liu,Zheng Li,Ya Zhang

doi:10.1063/1.5042018

Abstract

In order to improve the radiation resistance of semiconductor detector, 3D trench electrode Si detector structures have been proposed by the Brookhaven National Laboratory (BNL) in 2009. In this paper, we propose a 3D trench electrode Si detector with adjustable central collection electrode, which integrates advantages of cylindrical units and parallel units. For those combined units, we use 1D Poisson equation as the first order approximation to study the changing of depletion in different regions. These results have been compared to those obtained from the full 3D simulation using a 3D-TCAD tool. According to calculations, we design a 3D trench electrode Si detector with adjustable central collection electrode. Furthermore, electrical characteristics of this type of detectors with different lengths of central collection electrode (lp+) have been simulated using the 3D-TCAD. Regarded as the main factor of signal-noise ratio, the geometric capacitance obtained from Silvaco TCAD simulations is compared with which is calculated by physical models when detectors size varies. Finally, the physic model of charge collection is established using Ramo theorem. The CCE (Charge Collection Efficiency) of detector unit is studied with this model (after Φ=1016 neq/cm2, average CCE is 38%).

Highlights

Widely used in high energy and nuclear physics experiments, suffers severe radiation damages that lead to degradations in detector performance
We will present the following in the paper: 1) how to make homogeneous extensions the depletion depths in the two different units; 2) simulation results of electrical characteristics profiles for the new detector cells with different central collection electrode lengths; and 3) a physic model of Collection Efficiency (CCE) for the new detector cell structure
For Si detector applications in current high energy physics experiments, such as those in LHC at CERN, the main effort has been directed so far towards the improvement of the detector full depletion voltage,[16] which leads to the increase of detector sensitive volume and the detector charge collection efficiency (CCE)

Summary

INTRODUCTION

Widely used in high energy and nuclear physics experiments, suffers severe radiation damages that lead to degradations in detector performance. Because 3D trench electrode Si detector structures have more uniform electric field,[11] it is superior as compared to 3D column electrode detector in radiation tolerance. It has many advantages in performance for high-energy physics applications, the cell size of a 3D trench electrode Si detector with a column central electrode is limited by the electrode spacing. In this paper, based on their study, we will study the detector’s full depletion voltages (V fd) and electric fields profiles in different directions (x and y directions in Fig. 1), and propose a better cell structure (combining a cylindrical unit and a parallel plate unit as the trench electrode, and an “adjustable central collection electrode”). We will present the following in the paper: 1) how to make homogeneous extensions the depletion depths in the two different units; 2) simulation results of electrical characteristics profiles for the new detector cells with different central collection electrode lengths; and 3) a physic model of CCE for the new detector cell structure

DESIGNS

Potential and electrical field

Geometric capacitance

Findings

CONCLUSION