Skip to Main content Skip to Navigation
Journal articles

Increasing the scope and precision of the steady-state photocarrier grating technique by measuring the photocurrents at several voltages

Abstract : Abstract The steady-state photocarrier grating (SSPG) experiment is a popular technique for extracting the minority carrier diffusion length of photoconductive thin films in coplanar configuration. The diffusion length is basically obtained from the measurement of the steady-state photocurrent produced by a low applied voltage while the material is illuminated by two monochromatic laser beams of different intensities that interfere between the electrical contacts of the sample. Despite its simplicity and popularity, it is well known that the technique can overestimate the minority carrier diffusion length in some samples. In this paper, we show that the precision of the technique can be substantially increased by performing the same experiment at different voltages. Additionally, we show how to estimate fundamental material parameters from the experiment, such as the density of states at the majority carrier quasi-Fermi energy and the ratio between the recombination states’ capture coefficient and mobility of majority carriers. First, we show that the procedures found in the literature for correcting the overestimation produced by the standard technique do not work properly due to an oversimplification in the modeling. Then, we use a numerical simulation of an unintentionally-doped hydrogenated-amorphous-silicon-like material to evaluate the precision of the new formulas and procedures presented. We clarify the conditions under which the standard SSPG technique produces large overestimations. In these cases, we show that the precision of the new procedure can be more than ten times higher. Finally, we use the standard and the new method to characterize a hydrogenated amorphous (a-Si:H) and a hydrogenated polymorphous (pm-Si:H) silicon sample at different temperatures. We observe that the overestimations produced by the standard technique increase with the ratio between the majority and minority carrier diffusion lengths and the ratio between the recombination states’ capture coefficient and mobility of majority carriers.
Document type :
Journal articles
Complete list of metadata

https://hal-centralesupelec.archives-ouvertes.fr/hal-03404160
Contributor : Christophe Longeaud Connect in order to contact the contributor
Submitted on : Tuesday, October 26, 2021 - 2:44:03 PM
Last modification on : Tuesday, November 16, 2021 - 4:27:28 AM

Files

Manuscript3.pdf
Files produced by the author(s)

Identifiers

Citation

Leonardo Kopprio, Christophe Longeaud. Increasing the scope and precision of the steady-state photocarrier grating technique by measuring the photocurrents at several voltages. Semiconductor Science and Technology, IOP Publishing, 2021, 36 (12), pp.125003. ⟨10.1088/1361-6641/ac271b⟩. ⟨hal-03404160⟩

Share

Metrics

Record views

17

Files downloads

17