Minority Carrier Lifetime Test With a 3-D Printed Dielectric-Filled Waveguide Probe and Microwave Photoconductivity Decay Technique

With a low-cost fabricated (3-D printed dielectric part and metallization using adhesive copper tape) open-ended rectangular waveguide as a transceiver probe, the groups of microwave photoconductive decay experiments are presented to study the influence of excitation frequency on system performance, such as sensitivity and signal-to-noise ratio (SNR). First, to observe the effect of excitation frequency on the waveguide probe’s reflection coefficient, a microwave photoconductivity decay (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-PCD) setup based on a one-port vector network analyzer is presented. Then, another <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-PCD setup based on conventional architecture is presented for carrier lifetime testing. A standard waveguide probe working at similar frequency band is also used as a benchmark probe. Experimental results show that the proposed 3-D printed waveguide probe offers <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10\times $ </tex-math></inline-formula> improved measurement sensitivity compared to the standard waveguide. For the used setup in this work, when excitation power is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ge 10$ </tex-math></inline-formula> dBm, by properly selecting the excitation frequency, the SNR of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-PCD system can be improved by at least 10 dB. A detailed analysis of the mechanism of SNR improvement is also presented. The proposed low-cost 3-D printed dielectric-filled waveguide probe provides an alternative for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-PCD systems.