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Characterization of silicon heterojunctions for solar cells.

Kleider JP, Alvarez J, Ankudinov AV, Gudovskikh AS, Gushchina EV, Labrune M, Maslova OA, Favre W, Gueunier-Farret ME, Roca I Cabarrocas P, Terukov EI - Nanoscale Res Lett (2011)

Bottom Line: This is in good agreement with planar conductance measurements that show a large interface conductance.It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions.These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Génie Electrique de Paris, CNRS UMR 8507, SUPELEC, Univ P-Sud, UPMC Univ Paris 6, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex, France. jean-paul.kleider@lgep.supelec.fr.

ABSTRACT
Conductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions. These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

No MeSH data available.


Modeling of the (p) a-Si:H/(n) c-Si heterojunction at equilibrium for various values of the valence band offset. (a) band diagram, and (b) free hole concentration profile.
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Figure 9: Modeling of the (p) a-Si:H/(n) c-Si heterojunction at equilibrium for various values of the valence band offset. (a) band diagram, and (b) free hole concentration profile.

Mentions: Similar simulations were performed for the (p) a-Si:H/(n) c-Si heterojunction. The band gap of a-Si:H also was taken at Eg = 1.75 eV, and the position of the Fermi level was fixed at 0.45 eV, which is a reasonable value for p-type a-Si:H, in agreement with our conductivity measurements. After having introduced the a-Si:H parameters, we combined the a-Si:H layer with an n-type c-Si substrate with Nd = 2 × 1015 cm-3 (corresponding to the resistivity value) to simulate the (p) a-Si:H/(n) c-Si heterojunction. Calculated band diagram and evaluated hole concentration profiles for different values of valence band offset ΔEV = EVc-Si - EVa-Si:H are shown in Figure 9a,b, respectively. Drastic increase of hole concentration is observed in (n) c-Si layer near the interface for increasing values of band offset, with the appearance of a strong inversion layer for ΔEV > 0.2 eV. Thus, simulations of both (n) a-Si:H/(p) c-Si and (p) a-Si:H/(n) c-Si heterojunctions show the appearance of a strong inversion interface region above a given value of band offset. The planar conductance can be related to the carrier density profile. Indeed, the conductance of the strong inversion channel can be written


Characterization of silicon heterojunctions for solar cells.

Kleider JP, Alvarez J, Ankudinov AV, Gudovskikh AS, Gushchina EV, Labrune M, Maslova OA, Favre W, Gueunier-Farret ME, Roca I Cabarrocas P, Terukov EI - Nanoscale Res Lett (2011)

Modeling of the (p) a-Si:H/(n) c-Si heterojunction at equilibrium for various values of the valence band offset. (a) band diagram, and (b) free hole concentration profile.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211203&req=5

Figure 9: Modeling of the (p) a-Si:H/(n) c-Si heterojunction at equilibrium for various values of the valence band offset. (a) band diagram, and (b) free hole concentration profile.
Mentions: Similar simulations were performed for the (p) a-Si:H/(n) c-Si heterojunction. The band gap of a-Si:H also was taken at Eg = 1.75 eV, and the position of the Fermi level was fixed at 0.45 eV, which is a reasonable value for p-type a-Si:H, in agreement with our conductivity measurements. After having introduced the a-Si:H parameters, we combined the a-Si:H layer with an n-type c-Si substrate with Nd = 2 × 1015 cm-3 (corresponding to the resistivity value) to simulate the (p) a-Si:H/(n) c-Si heterojunction. Calculated band diagram and evaluated hole concentration profiles for different values of valence band offset ΔEV = EVc-Si - EVa-Si:H are shown in Figure 9a,b, respectively. Drastic increase of hole concentration is observed in (n) c-Si layer near the interface for increasing values of band offset, with the appearance of a strong inversion layer for ΔEV > 0.2 eV. Thus, simulations of both (n) a-Si:H/(p) c-Si and (p) a-Si:H/(n) c-Si heterojunctions show the appearance of a strong inversion interface region above a given value of band offset. The planar conductance can be related to the carrier density profile. Indeed, the conductance of the strong inversion channel can be written

Bottom Line: This is in good agreement with planar conductance measurements that show a large interface conductance.It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions.These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Génie Electrique de Paris, CNRS UMR 8507, SUPELEC, Univ P-Sud, UPMC Univ Paris 6, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex, France. jean-paul.kleider@lgep.supelec.fr.

ABSTRACT
Conductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions. These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

No MeSH data available.