Deep levels in silicon Schottky junctions with embedded arrays of β-FeSi2 nanocrystallites

Abstract

Schottky contacts on p-type silicon, with embedded arrays of β-FeSi2 nanocrystallites, were studied by current-voltage (I-V), deep level transient spectroscopy (DLTS), and low-frequency noise measurements. Forward I-V characteristics on logarithmic scale indicate that space-charge limited current (SCLC) dominates the carrier transport in these diodes. From an analysis of the SCLC characteristics, we found that two arrays of β-FeSi2 nanocrystallites induce a trap level at 320meV above the valence band edge with concentration of 5×1014cm−3, which is in relatively good agreement with the trap detected by DLTS. By inserting ten arrays of β-FeSi2 nanocrystallites, two trap levels at 300 and 340meV with concentrations of 2.6×1014 and 1.1×1015cm−3, respectively, were found from the SCLC analysis. By increasing the number of the inserted arrays of β-FeSi2 nanocrystallites from 2 to 10, a trap at 402meV with concentration of 6.5×1015cm−3 has been detected by DLTS, failing to detect the second trap observed by SCLC measurements. The normalized power spectral density SI∕I2 vs V exhibits a peak at the transition voltage from the trap-filling regime to the SCLC regime, corresponding to a deep trap level. It is demonstrated that the noise technique is more sensitive than the SCLC and DLTS techniques in extracting information about the deep trap parameters.