Erik Stensrud Marstein

2D back-side diffraction grating for improved light trapping in thin silicon solar cells

Light-trapping techniques can be used to improve the efficiency of thin silicon solar cells. We report on numerical investigation of a light trapping design consisting of a 2D back-side diffraction grating in combination with an aluminum mirror and a spacing layer of low permittivity to minimize parasitic absorption in the aluminum. The light-trapping design was compared to a planar reference design with antireflection coating and back-side aluminum mirror. Both normally and obliquely incident light was investigated. For normal incidence, the light trapping structure increases the short circuit current density with 17% from 30.4 mA/cm(2) to 35.5 mA/cm(2) for a 20 microm thick silicon solar cell. Our design also increases the current density in thinner cells, and yields higher current density than two recently published designs for cell thickness of 2 and 5 microm, respectively. The increase in current may be attributed to two factors; increased path length due to in-coupling of light, and decreased parasitic absorption in the aluminum due to the spacing layer.

Comparison of periodic light-trapping structures in thin crystalline silicon solar cells

Material costs may be reduced and electrical properties improved by utilizing thinner solar cells. Light trapping makes it possible to reduce wafer thickness without compromising optical absorption in a silicon solar cell. In this work we present a comprehensive comparison of the light-trapping properties of various bi-periodic structures with a square lattice. The geometries that we have investigated are cylinders, cones, inverted pyramids, dimples (half-spheres), and three more advanced structures, which we have called the roof mosaic, rose, and zigzag structure. Through simulations performed with a 20 μm thick Si cell, we have optimized the geometry of each structure for light trapping, investigated the performance at oblique angles of incidence, and computed efficiencies for the different diffraction orders for the optimized structures. We find that the lattice periods that give optimal light trapping are comparable for all structures, but that the light-trapping ability varies considerably between th...

Oxidation Effects on Graded Porous Silicon Anti-Reflection Coatings

Efficient anti-reflection coatings (ARC) improve the light collection and thereby increase the current output of solar cells. By simple electrochemical etching of the Si wafer, porous silicon (PS) layers with excellent broadband anti-reflection properties can be fabricated. In this work, ageing of graded PS has been studied using Spectroscopic Ellipsometry, Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. During oxidation of PS elements such as pure Si (Si

Double layer anti-reflective coatings for silicon solar cells

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Optimization of multilayer porous silicon antireflection coatings for silicon solar cells

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Studying Light-Induced Degradation by Lifetime Decay Analysis: Excellent Fit to Solution of Simple Second-Order Rate Equation

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Hydrogen complexes in Zn deficient ZnO

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Direct monitoring of minority carrier density during light induced degradation in Czochralski silicon by photoluminescence imaging

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Introduction of Si∕SiO2 interface states by annealing Ge-implanted films

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Hydrogen Release and Defect Formation During Heat Treatments of SiNx:H/a-Si: H Double Passivation Layer on C-SI Substrate

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