Scanning capacitance spectroscopy on n+-p asymmetrical junctions in multicrystalline Si solar cells

Abstract

Modeling of silicon nanocrystals based down-shifter for enhanced silicon solar cell performance J. Appl. Phys. 111, 034303 (2012) Analytical solution for the photocurrent of solar cells with internal reflection J. Appl. Phys. 111, 034502 (2012) On the design and applicability of nanowire solar cells using low-grade semiconductors J. Appl. Phys. 111, 034501 (2012) Fundamental limits in the external quantum efficiency of single nanowire solar cells Appl. Phys. Lett. 99, 263102 (2011) A semi-analytical model for semiconductor solar cells J. Appl. Phys. 110, 123104 (2011) Additional information on J. Appl. Phys. We report on a scanning capacitance spectroscopy (SCS) study on the n þ -p junction of multicrystalline silicon solar cells. We found that the spectra taken at space intervals of $10 nm exhibit characteristic features that depend strongly on the location relative to the junction. The capacitance-voltage spectra exhibit a local minimum capacitance value at the electrical junction, which allows the junction to be identified with $10-nm resolution. The spectra also show complicated transitions from the junction to the n-region with two local capacitance minima on the capacitance-voltage curves; similar spectra to that have not been previously reported in the literature. These distinctive spectra are due to uneven carrier-flow from both the n-and p-sides. Our results contribute significantly to the SCS study on asymmetrical junctions.

Real-space microscopic electrical imaging of n+-p junction beneath front-side Ag contact of multicrystalline Si solar cells

“…The SCM signal decreases (or the image becomes darker) going into the emitter from the emitter/grid boundary, corresponding first to a decrease in n-doping concentration and then to entering the depletion region. 16 From a location in the depletion region (not necessarily the junction location), it increases to positive. Away from the junction region, the signal remains at a constant positive value corresponding to the p-doping concentration of the Si bulk.…”

“…On unipolar samples, the SCM dC/dV signal is about zero on both highly conductive (metallic) and insulating samples, small and large on high-and low-doped, and positive and negative on p-and n-doped samples, respectively. 14 On a bipolar structure such as a p-n junction, the SCM signal is rather complicated, 16 and the junction location deviates significantly from its apparent location with dC/dV ¼ 0.…”

A cross‐sectional scanning capacitance microscopy characterization of GaAs based solar cell structures

“…Measurement of local capacitance changes on sample cross‐section seems to be very interesting from the characterization point of view of optoelectronic devices. So far SCM method was successfully applied for characterization of both, crystalline and multicrystalline silicon based solar cells, cadmium telluride and copper indium gallium selenide solar cells . In case of III‐V semiconductors the characterization results of InGaAs/InP infrared photodetectors , GaAs pn junctions with embedded ErAs nanoparticles or InAs quantum dots in GaAs matrix were reported .…”

Locating the electrical junctions in Cu(In,Ga)Se2 and Cu2ZnSnSe4 solar cells by scanning capacitance spectroscopy

“…This is especially necessary for thin‐film photovoltaics because the surface band bending is expected to be inhomogeneous among the multiple layers and within a polycrystalline layer. Because of its high resolution, SCM/SCS measurements would provide vital information for junction determination and carrier characteristics in the junction/depletion area .…”