Transient mobility in silicon as seen by a combination of free-carrier absorption and resonance-coupled photoconductive decay

Published

March 12, 2013

Author(s)

Ari D. Feldman, John H. Lehman, Richard K. Ahrenkiel

Abstract

The combination of the resonance-coupled photoconductive decay (RCPCD) apparatus and a pump-probe free carrier absorption experiment results in a method of viewing transient mobility. RCPCD uses an Nd:YAG laser operating at 1064 nm to pump the p-type silicon wafer, and a microwave coil antenna detects the transient excess-carrier concentration. The pump-probe experiment uses the same pump laser and a 10.6υm CO₂ laser with HgCdTe photodetector to measure the transient change in absorption. The change in conductivity detected by RCPCD is directly proportional the excess-carrier concentration ({Δ}n) and mobility (υ), whereas the pump-probe experiment has an inversely proportional relationship. By mathematically combining these signals at equivalent optical fluxes, a quantity proportional to the mobility emerges. The mobility is shown to vary both temporally and with respect to injection, countering the assumption that mobility is constant for photoconductive decay measurements. Theory and results are discussed within.

Citation

Journal of Applied Physics

Volume

113

Pub Type

Journals

Keywords

minority-carrier lifetime, mobility, photoconductive decay, photovoltaic, pump-probe

Citation

Feldman, A. , Lehman, J. and Ahrenkiel, R. (2013), Transient mobility in silicon as seen by a combination of free-carrier absorption and resonance-coupled photoconductive decay, Journal of Applied Physics (Accessed May 10, 2025)