A T-CAD analysis & comparison of the semi-insulator and dielectric passivated silicon microstrip detector: impact on breakdown voltage

In this paper, the influence of various physical and geometrical parameters such as permittivity of passivant dielectric, passivation layer thickness, junction depth, n-layer thickness and fixed oxide charge on the breakdown voltage of semi-insulator passivated silicon microstrip detector is investigated using a 2-dimensional T-CAD simulator. Comparisons of this structure with most commonly used dielectric are also studied. The breakdown voltage of semi-insulator passivated devices remains nearly constant over a wide variation in passivation layer thickness for all values of junction depth, indicating that passivation layer thickness is not an important design parameter in high voltage planar devices passivated with semi-insulator. The influence of the fixed oxide charge on the breakdown voltage of semi-insulator passivated device is found to be negligible. Thus, the present study shows that the semi-insulator passivated structures allow for a design of Si strip detectors reducing dead layer and making the detectors more suitable for next generation high energy physics experiments and improve the breakdown voltage. In contrast, dielectric passivated films are preferred if compactness of detectors are desired. A good agreement between the experiment and simulation is also observed.