Field-effect passivation on silicon nanowire solar cells

Mallorquí, Anna Dalmau; Alarcón-Lladó, Esther; Mundet, Ignasi Canales; Kiani, Amirreza; Demaurex, Bénédicte; Wolf, Stefaan De; Menzel, Andreas M.; Zacharias, Margit; Morral, Anna Fontcuberta i

doi:10.1007/s12274-014-0551-7

Cited by 74 publications

(66 citation statements)

References 39 publications

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“…However, the properties of the Si/Al 2 O 3 interface cannot explain alone the similar passivation levels obtained in planar and nanostructured silicon due to much larger surface area present in the latter. Consequently, it has been speculated that the efficient black silicon passivation by Al 2 O 3 could arise from the strong field-effect generated by the fixed Al 2 O 3 charge that leads to repulsion of charge carriers from the entire black silicon needles [6,14]. However, no clear evidence has been given so far.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Atomic Layer Deposited Al2O3 field-effect passivation in black silicon

Gastrow

Alcubilla

Ortega

et al. 2015

Solar Energy Materials and Solar Cells

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We demonstrate that n-type black silicon can be passivated efficiently using Atomic Layer Deposited (ALD) Al 2 O 3 , reaching maximum surface recombination velocities below 7 cm/s. We show that the low surface recombination velocity results from a higher sensitivity of the nanostructures to surface charge and from the absence of surface damage after black silicon etching. The surface recombination velocity is shown to be inversely proportional to the fourth power of the negative charge in contrast to the quadratic dependence observed in planar surfaces. This effect compensates the impact of the increased surface area in the nanostructures and extends the potential of black silicon for instance to n-type Interdigitated Back Contact (IBC) cells.

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Section: Introductionmentioning

confidence: 99%

Analysis of the Atomic Layer Deposited Al2O3 field-effect passivation in black silicon

Gastrow

Alcubilla

Ortega

et al. 2015

Solar Energy Materials and Solar Cells

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“…[ 7,13 ] In addition, the radial junction contributes to a lower surface recombination rate for the overall device. [ 14,15 ] Here, we investigate different doping methods applied to silicon micropillars, in order to obtain optimal geometry control of the pillars and p/n junctions therein, as well as ease of utilization for further applications. Silicon-based p/n junctions can be realized by various doping methods.…”

Section: Introductionmentioning

confidence: 99%

Controlled Doping Methods for Radial p/n Junctions in Silicon

Elbersen

Tiggelaar

Milbrat

et al. 2014

Advanced Energy Materials

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P/n and n/p junctions with depths of 200 nm to several micrometers have been created in flat silicon substrates as well as on 3D microstructures by means of a variety of methods, including solid source dotation (SSD), low‐pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition, and plasma‐enhanced chemical vapor deposition. Radial junctions in Si micropillars are inspected by optical and scanning electron microscopies, using a CrO3‐based staining solution, which enables visualization of the junction depth. When applying identical‐doping parameters to flat substrates, ball grooving, followed by staining and optical microscopy, yields similar junction depth values as high‐resolution scanning electron microscopy imaging on stained cross‐sections and secondary ion mass spectrometry depth profilometry. For the investigated 3D microstructures, doping based on SSD and LPCVD give uniform and conformal junctions. Junctions made with SSD‐boron doping and CVD‐phosphorus doping could be accurately predicted with a model based on Fick's diffusion law. 3D‐microstructured silicon pillar arrays show an increased efficiency for sunlight capturing. The functionality of micropillar arrays with radial junctions is evidenced by improved short‐circuit current densities and photovoltaic efficiencies compared with flat surfaces, for both n‐ and p‐type wafers (average pillar arrays efficiencies of 9.4% and 11%, respectively, compared with 8.3% and 6.4% for the flat samples).

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“…15-19 Different passivation methods have been employed in the past, notably capping of the free surfaces with a higher bandgap shell around the nanowire. [20][21][22] Nevertheless, capping also modifies the nature of the surface. Several effects have been reported, such as band bending at the interface leading to the accumulation of the charge at the interface or piezo electric strain.…”

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confidence: 99%

Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes

et al. 2017

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III-V nanostructures have the potential to revolutionize optoelectronics and energy harvesting. For this to become a reality, critical issues such as reproducibility and sensitivity to defects should be resolved. By discussing the optical properties of MBE grown GaAs nanomembranes we highlight several features that bring them closer to large scale applications. Uncapped membranes exhibit a very high optical quality, 1 arXiv:1704.08477v1 [cond-mat.mes-hall] 27 Apr 2017 expressed by extremely narrow neutral exciton emission, allowing the resolution of the more complex excitonic structure for the first time. Capping of the membranes with an AlGaAs shell results in a strong increase of emission intensity but also to a shift and broadening of the exciton peak. This is attributed to the existence of impurities in the shell, beyond MBE-grade quality, showing the high sensitivity of these structures to the presence of impurities. Finally, emission properties are identical at the sub-micron and sub-millimeter scale, demonstrating the potential of these structures for large scale applications.Keywords: GaAs/AlGaAs nano mebranes, photoluminescence, electronic and optical properties of ensemble vs single nano membrane Nanowires (NWs) are filamentary crystals with a diameter in the sub-micrometer down to nanometer range. Their special morphology, dimensions and high surface-to-volume ratio are often translated into advantageous optical and electrical properties. As a consequence, they have been widely used in electronics, 1-5 optoelectronics, 6,7 solar cells 8-11 and sensors. 12,13 If not adequately passivated, the surface recombination can limit the optical performance of the NWs. 14 In addition, surface depletion can also affect the volume distribution and separation of the carriers in the NW. 15-19 Different passivation methods have been employed in the past, notably capping of the free surfaces with a higher bandgap shell around the nanowire. [20][21][22] Nevertheless, capping also modifies the nature of the surface. Several effects have been reported, such as band bending at the interface leading to the accumulation of the charge at the interface or piezo electric strain. [23][24][25][26][27] In addition, the AlGaAs alloy typically used for capping GaAs nanowires is generally inhomogeneous, with directed and random segregation of Ga and Al forming respectively Al-rich ridges and Ga-rich nanoscale islands . 28,29 Simultaneously, III-V NWs can suffer from twin defects and polytypism, 30,31 which adversely affect their electronic and optical properties. 32-34 With a judicious optimization of growth conditions, single NWs with a pure zinc-blende or wurzite structure can be obtained. [35][36][37] Still, the optical and electronic properties tend to fluctuate considerably from NW to NW, 2 which precludes the proper control of the response of an ensemble of nanowires.Recently, alternative approaches to obtain defect-free nano structures have been proposed. Particularly promising is the inversion of polarity from B to A...

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Field-effect passivation on silicon nanowire solar cells

Cited by 74 publications

References 39 publications

Analysis of the Atomic Layer Deposited Al2O3 field-effect passivation in black silicon

Analysis of the Atomic Layer Deposited Al2O3 field-effect passivation in black silicon

Controlled Doping Methods for Radial p/n Junctions in Silicon

Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes

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