The nature of silicon PN junction impedance at high frequency

• Main Authors: van Nijen, David A, Procel, Paul, van Swaaij, René A. C. M. M, Zeman, Miro, Isabella, Olindo, Manganiello, Patrizio
• Format: Journal Article
• Language: English
• Published: 10-09-2024
• Subjects: Physics - Applied Physics
• DOI: 10.48550/arxiv.2409.06749

A thorough understanding of the small-signal response of solar cells can
reveal intrinsic device characteristics and pave the way for innovations. This
study investigates the impedance of crystalline silicon PN junction devices
using TCAD simulations, focusing on the impact of frequency, bias voltage, and
the presence of a low-high (LH) junction. It is shown that the PN junction
exhibits a fixed $RC$-loop behavior at low frequencies, but undergoes
relaxation in both resistance $R_j$ and capacitance $C_j$ as frequency
increases. Moreover, it is revealed that the addition of a LH junction impacts
the impedance by altering $R_j$, $C_j$, and the series resistance $R_s$.
Contrary to conventional modeling approaches, which often include an additional
$RC$-loop to represent the LH junction, this study suggests that such a
representation does not represent the underlying physics, particularly the
frequency-dependent behavior of $R_j$ and $C_j$.