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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.


Topography and electrical image obtained after HF dip at the cleaved section of an (n) a-Si:H/(p) c-Si heterojunction. Left: topography; right: resistance image.
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Figure 5: Topography and electrical image obtained after HF dip at the cleaved section of an (n) a-Si:H/(p) c-Si heterojunction. Left: topography; right: resistance image.

Mentions: In order to minimize the effects of surface oxide and surface states, CP-AFM measurements were performed at LGEP under nitrogen atmosphere immediately after having dipped the sample in an HF solution. This treatment is known to passivate the silicon surface by reducing the density of silicon dangling bonds, thus minimizing the potential effect of surface states on the surface band bending. Figure 5 illustrates an example of topographical and electrical image of the cleaved section obtained under these conditions with, from top to bottom, the n-type a-Si:H layer (= 300 nm) and the p-type c-Si substrate. Contrary to Figure 4, the ITO contact is not observed since it has been partially removed after the HF dip. Compared to results of Figure 4, with the improved measurement procedure, a conductive channel at the (n) a-Si:H/(p) c-Si interface is even more clearly observed. The topographic and electrical profiles along the heterointerface presented on Figure 6 show a flat cleaved surface and a higher electrical contrast between the conductive channel and both the a-Si:H layer and the c-Si substrate. In addition, the electrical image in the c-Si also shows a region with increasing conductivity of about 1 μm width when sweeping away from the a-Si:H/c-Si interface. This can be linked to the depleted space charge region in the low-doped (p) c-Si (Na < 1015 cm-3), which has a width close to 1 μm.


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)

Topography and electrical image obtained after HF dip at the cleaved section of an (n) a-Si:H/(p) c-Si heterojunction. Left: topography; right: resistance image.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Topography and electrical image obtained after HF dip at the cleaved section of an (n) a-Si:H/(p) c-Si heterojunction. Left: topography; right: resistance image.
Mentions: In order to minimize the effects of surface oxide and surface states, CP-AFM measurements were performed at LGEP under nitrogen atmosphere immediately after having dipped the sample in an HF solution. This treatment is known to passivate the silicon surface by reducing the density of silicon dangling bonds, thus minimizing the potential effect of surface states on the surface band bending. Figure 5 illustrates an example of topographical and electrical image of the cleaved section obtained under these conditions with, from top to bottom, the n-type a-Si:H layer (= 300 nm) and the p-type c-Si substrate. Contrary to Figure 4, the ITO contact is not observed since it has been partially removed after the HF dip. Compared to results of Figure 4, with the improved measurement procedure, a conductive channel at the (n) a-Si:H/(p) c-Si interface is even more clearly observed. The topographic and electrical profiles along the heterointerface presented on Figure 6 show a flat cleaved surface and a higher electrical contrast between the conductive channel and both the a-Si:H layer and the c-Si substrate. In addition, the electrical image in the c-Si also shows a region with increasing conductivity of about 1 μm width when sweeping away from the a-Si:H/c-Si interface. This can be linked to the depleted space charge region in the low-doped (p) c-Si (Na < 1015 cm-3), which has a width close to 1 μm.

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.