Metal-doped silicon diodes for radiation sensing applications

Abstract

Using an ion implantation method, crystalline silicon (Si) of different concentration types (n-, p-, and i-types) was doped with iron (Fe) and cadmium (Cd) metals. Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) techniques were used to confirm the presence of the doped metals in Si. The effect of Fe- and Cd-doping on the electrical properties of the fabricated Si diodes was investigated using current-voltage (I-V) and capacitance-voltage (C-V) techniques. The generation and recombination (g-r) centres have been induced in Si by metal-doping, as evidenced by a change in diode I-V trends from typical exponential to ohmic behaviour. The C-V trends, on the other hand, reveal that holes generated by metal-induced defects in Si are immobile, causing electrons stored in the space charge region (SCR) to dominate measured capacitance at a frequency of 5 kHz. I-V properties of the metal-doped based Si diodes are less sensitive to 4 MeV proton-irradiation, implying that Fe and Cd suppress radiation damage in Si. The findings in this study suggest that Fe and Cd are promising dopants in a study to improve Si radiation-hardness using a defect-engineering method. As a result, the research is crucial for an ongoing quest to enhance the efficiency of Si radiation detectors for current and future high-energy physics experiments and other applications.