Spatially Resolved Transient Current Technique Characterization of an Asymmetric p-i-p Silicon Diode Under Multi-Wavelength Excitation

This work presents an asymmetric p-i-p silicon diode structure (a-p-i-p) characterized using the Transient Current Technique (TCT) with a scanning pulsed laser system. The device, fabricated on n-type silicon (3–5 Ω·cm) with two identical p+-doped meandering line electrodes (one of which is obscured by a black resin layer), was tested in photovoltaic mode (zero bias) under laser excitation at 660 nm, 980 nm, and 1064 nm wavelengths. The transient photocurrent response was recorded as the laser spot was scanned across the device surface with 0.01 mm spatial resolution. A pronounced wavelength-dependent response was observed: the shortest wavelength (660 nm) produced the largest transient current signals, while longer wavelengths (980 nm, 1064 nm) yielded progressively weaker responses. This study introduces a fundamentally new design paradigm that enables the p-i-p diode to operate in photovoltaic mode.