The analysis of the temperature dependence of photoconductive frequency-resolved spectroscopy in the presence of carrier trapping: Application to polycrystalline silicon

Abstract

The analysis of photoconductive frequency-resolved spectroscopy is developed for variable temperature measurements. It is shown that when the excess carrier kinetics is dominated by carrier trapping the technique can be used to obtain the major trap parameters. This analysis is applied as an example to polycrystalline silicon on insulator on silicon films and a dominant trap with an activation energy of 70 meV is identified.

Surface band-bending assessment by photocurrent techniques. Application to III - V semiconductors

“…where τ and g are the small-signal carrier lifetime and excitation function respectively. For the case of single and multiple trapping processes, the modifications to equation ( 1) have been described in detail in [1,2]. The solution of the above equation for a sinusoidal modulating frequency ω is well known:…”

“…The in-phase component decreases as frequency increases, showing its half-value at this same frequency. It is important to point out that under low injection level conditions and for low singletrap concentrations, the PCFRS Lorentzians will not shift in frequency with changes in the d.c. photon intensity [1]. Under these conditions, the temperature frequency dependence of the low-frequency Lorentzian peak allows one to obtain the activation energy of the trap.…”

“…As an alternative technique, requiring just ohmic contacts, photoconductivity spectroscopy has been proposed to characterize homogeneous samples. One such photoconductive characterization technique, socalled photoconductivity frequency resolved spectroscopy (PCFRS) [1,2], was proposed for the study of traps in semiconductors. In this technique, a photoconductive sample is illuminated by photons with energy above the bandgap and carrying a small amplitude modulation (AM) at a given frequency f .…”

Frequency-resolved microwave reflection photoconductance

“…In the analysis, a two level recombination/ trapping model is used. A similar model and its implication on photoconductive response in the frequency domain were recently analyzed by Lourenco et al, 10,11 but without including surface effects. Since the surface recombination process has a large impact on carrier kinetics, it cannot be neglected in a rigorous approach.…”