Application of Neon Ion Implantation to Generate Intermediate Energy Levels in the Band Gap of Boron-Doped Silicon as a Material for Photovoltaic Cells

Abstract

The aim of the work is to present the possibility of generating intermediate levels in the band gap of p-type silicon doped with boron by using neon ion implantation in the aspect of improving the efficiency of photovoltaic cells made on its basis. The work contains an analysis of the influence of the dose of neon ions on the activation energy value of additional energy levels. The article presents the results of measurements of the capacitance and conductance of silicon samples with a resistivity of ρ = 0.4 Ω cm doped with boron, the structure of which was modified in the implantation process with Ne+ ions with the energy E = 100 keV and three different doses of D = 4.0 × 1013 cm−2, 2.2 × 1014 cm−2 and 4.0 × 1014 cm−2, respectively. Activation energies were determined on the basis of Arrhenius curves ln(et(Tp)/Tp2) = f(1/kTp), where Tp is in the range from 200 K to 373 K and represents the sample temperature during the measurements, which were carried out for the frequencies fp in the range from 1 kHz to 10 MHz. In the tested samples, additional energy levels were identified and their position in the semiconductor band gap was determined by estimating the activation energy value. The conducted analysis showed that by introducing appropriate defects in the silicon crystal lattice as a result of neon ion implantation with a specific dose and energy, it is possible to generate additional energy levels ∆E = 0.46 eV in the semiconductor band gap, the presence of which directly affects the efficiency of photovoltaic cells made on the basis of such a modified material.