Characterization of deep-level defects in highly-doped silicon with asymmetric structure by transient capacitance spectroscopy

Deep-level transient spectroscopy (DLTS) is a widely used method to analyze the properties of deep defects in semiconductors. However, it has been rarely reported to measure the deep-levels of highly-doped silicon because the large leakage current badly affects the transient capacitance signal of DLTS technique, due to the trap occupancy dominated by thermal emission instead of capture of carriers. Herein, by employing an asymmetric structure to reduce leakage current, we observed two deep-level defect states of highly phosphorus-doped silicon (7 × 10¹⁷ cm⁻³) in the DLTS spectrum, corresponding to the E-center (vacancy-P trap) and doubly negative charged states. Furthermore, the photocurrent spectrum of the sample under 4 K shows two mid-infrared response peaks, arising from the photoexcitation behavior of the above two defects. This finding provides a new route to measure the deep-level defect properties of highly-doped semiconductor materials using DLTS method. It also suggests potential applications of photoexcitation activity of defects in photoelectric detection.