Production of p-Type Si/n-Type β-FeSi₂ Heterojunctions Using Facing-Targets Direct-Current Sputtering and Evaluation of Their Resistance and Interface State Density

Without a post-annealing procedure, the β-FeSi₂ thin films are epitaxially grown on Si(111) wafer substrates via facing-targets direct-current sputtering. During epitaxial growth, the temperature for heating of substrates is maintained at 600 °C. The resultant p-type Si/n-type β-FeSi₂ heterojunctions are produced. At room temperature, a large leakage current under an applied reverse bias voltage together with a small photo-detective performance is observed from the measured dark and irradiated current density–voltage curves of the created heterojunctions. Both of the conductance–voltage (G/ω–V) and capacitance–voltage (C–V) measurements at different frequencies (f) in the range of 5 kHz–1 MHz are performed in the dark at room temperature. The interface state density (N_ss) and series resistance (R_s) in the created p-type Si/n-type β-FeSi₂ heterojunctions are computed and analyzed from the measured C–V–f and G/ω–V–f curves. N_ss is found to be 3.48 × 10¹² eV⁻¹ cm⁻² at 5 kHz and decreased to 4.68 × 10¹¹ eV⁻¹ cm⁻² at 1 MHz. Moreover, the values of R_s at zero bias are 2.21 kΩ at 5 kHz and 13.66 Ω at 1 MHz. These results review the presence of N_ss and R_s in the created heterojunctions, and they can be the cause to degrade the heterojunction performance.