Steady‐State Photocarrier Grating Method

Brüggemann, R.

doi:10.1002/9783527699025.ch7

Cited by 2 publications

(8 citation statements)

References 59 publications

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“…In appendix A, we present the deduction of equations ( 10) and (11), and the expressions of the parameters Q + , Q − , τ r n , τ r p , γ n and γ p for an arbitrary density of monovalent localized states in the band-gap of the semiconductor.…”

Section: General Equationmentioning

confidence: 99%

“…Using equations (10) and (11) and some algebra, we can rewrite equations ( 4)-( 6) in a compact way, which makes explicit the dependence of ∆J/J 0 with k 2 and ξ 2 ext…”

Section: General Equationmentioning

confidence: 99%

“…Figure 1 presents the basic experimental setup used in the SSPG technique [11]. The generation rate in the material (equation ( 1)) is produced by the interference of two monochromatic light beams of different intensities.…”

Section: Experimental Configurationmentioning

confidence: 99%

“…The low-voltage SSPG estimates the ambipolar diffusion length, L 2 amb = (γ n + γ p ) L 2 p , by fitting the experimental values of β vs k 2 for a low applied electric field with the RZW formula (equation ( 24)) [1,11]. The L 2 amb relative errors obtained from this approach in an n-type semiconductor can be estimated from equation ( 25)…”

Section: Validity Of the Low-voltage Approachmentioning

confidence: 99%

“…Over the years, the SSPG technique has become a standard method for material characterization in several laboratories [11], where it has been effectively applied to a-Si:H and its alloys, hydrogenated microcrystalline silicon and germanium, chalcopyrite and III-V semiconductors [12,13], and also to hybrid perovskites [14][15][16]. We focus the analysis on a-Si:H-like materials because they are one of the most thoroughly studied thin-film materials in the bibliography, and there is a broad consensus on their basic optoelectronic modeling [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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

Kopprio¹,

Longeaud²

2021

Semicond. Sci. Technol.

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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.

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Section: General Equationmentioning

confidence: 99%

“…Using equations (10) and (11) and some algebra, we can rewrite equations ( 4)-( 6) in a compact way, which makes explicit the dependence of ∆J/J 0 with k 2 and ξ 2 ext…”

Section: General Equationmentioning

confidence: 99%

Section: Experimental Configurationmentioning

confidence: 99%

Section: Validity Of the Low-voltage Approachmentioning

confidence: 99%