Titelfoto. Advanced Laser Beam Shaping - for Optimized Process Results and Quality Inspection in the PV Production - Maja Thies.

Transcription

1 2010 LIMO Lissotschenko Mikrooptik GmbH Titelfoto Advanced Laser Beam Shaping - for Optimized Process Results and Quality Inspection in the PV Production - Maja Thies Photonics Key Technology for an Effective and Cost-Efficient PV Production 27 th September 2012

2 LIMO Solar Cell Solution - Overview Gaussian-to-top-hat conversion for laser direct patterning Multi-spot-generators for fast parallel processing Laser line generators for material properties engineering Off-axis illumination for inline quality control 2

3 LIMO Solar Cell Solution - Overview Gaussian-to-top-hat conversion for laser direct patterning Multi-spot-generators for fast parallel processing Laser line generators for material properties engineering Off-axis illumination for inline quality control 3

4 Beam Shaping Principle: Phase Shifting (for single mode lasers) Collimated Gaussian beam Free-form phase shifting element Generated Top-hat profile Simulation Measurement 4

5 Overview g2t Converter Overview g2t converters Wavelength [nm] Top hat [mm] WD [mm] DOF [mm] x x ±0.04 ± x x x x x x ±8 ±0.05 ±0.30 ±0.40 ±10.0 ±0.20 2nd converter generation with increased depth of field 9.6 x ±13 5

6 Laser Direct Patterning Gaussian Profile vs. Top Hat Profiles Steep edges Uniform patterning 6

7 Laser Direct Patterning Gaussian Profile vs. Top Hat Profiles Higher efficiency Energy content Increase of Efficiency 2D Profile Gauss Top-Hat Top Hat- Gauss FW90% 36% 68% +80% FW50% 74% 90% +20% Smooth edges, increased throughput 7

8 Laser Structuring of Thin Film Solar Cells 8

9 Patterning Examples SnO 2 Gaussian profile Top hat profile Polyimide Structuring Advantages Smooth edges Reduced heat affected zone, no delamination Precise thin film ablation, no damage of underlying material 9

10 LIMO g2t -Scan-System Single Mode Laser Attenuator Beam Expander g2t 30 mm Scanner XY-stage XY-stage g2tf-theta lens Specification ~ 200 mm Wavelength 532 nm Top hat size 50 µm Scan area 156 x156 mm² ~ 500 mm ~ 400 mm Advantages Top hat patterning High speed Precision Target 10

11 Laser Fired Contacts Local contacts through the passivation are created with single laser pulses contact energy threshold Energy high above the contact threshold induces damage to the Silicon substrate 11

12 LIMO Solar Cell Solution - Overview Gaussian-to-top-hat conversion for laser direct patterning Multi-Spot-generators for fast parallel processing Laser line generators for material properties engineering Off-axis illumination for inline quality control 12

13 LIMO Proprietary Technology NO quantization error NO scattering on the relief discontinuities NO surface defects HIGH damage threshold Efficiency > 95% HIGH homogeneity also coherent beam combining 13

14 Z, um Kinoform Beam Splitters Romero, L.A., Dickey, F. M., "Theory of optimal beam splitting by phase gratings. I. One-dimensional gratings", J. Opt. Soc. Am. A, 24, (2007) 1 DOE Profile x, mm Quartz, Pitch 20 µm, λ = 1064 nm, inter-beam angle i = /Pitch = 53.2 mrad 14

15 Measurement Data: Power Distribution Inhomogeneity: ± 5% Total Efficiency: 95 ± 2 % Foto 2 15

16 LIMO Solar Cell Solution - Overview Gaussian-to-top-hat conversion for laser direct patterning Multi-spot-generators for fast parallel processing Laser line generators for material properties engineering Off-axis illumination for inline quality control 16

17 LIMO Line Laser Punctiform laser source Discontinous, multidirectional heat distribution L³ - Limo Line Laser Continous linear heat distribution Punctiform laser source L³ - Limo Line Laser 17

18 Crystallization of a-si Thin Films on Glass Using a Diode Laser Laser source 450W, 808 nm direct diode line beam 12 mm x 100 µm Material 200 nm a-si on glass Process First results (R&D) single scan at a scanning speed of 33 mm/s crystal grain size > 100 µm increased charge carrier mobility in the absorber layer reduced surface resistance (R sq ) Pictures: IPHT, Jena Foto 1 Foto 1 Foto µm 18

19 LIMO Solar Cell Solution - Overview Gaussian-to-top-hat conversion for laser direct patterning Multi-spot-generators for fast parallel processing Laser line generators for material properties engineering Off-axis illumination for inline quality control 19

20 Inline Quality Control Advantages of quality assurance by photoluminescence At various inline production steps possible Contactless and non-destructive Cost-efficient Fast, high throughput Technical Specifications of illumination source Top-Hat profile under an illumination angle of 35 Field size: > 156 x 156 mm² Power: variable Wavelength: 790 / 808 nm Inhomogeneity: (lmax-lmin)/(lmax+lmin) < 7.5 % 20

21 Asymmetric Homogenizers Give Best Uniformity Symmetric homogenizer Inhomogeneity ~ 25 % Asymmetric homogenizer Inhomogeneity < 7.5 % 21

22 Line Laser for Scanning of the Solar Cell Technical specifications for laser line generator: Compactness Line dimensions: 165 mm x 3 mm Power: 40 W Wavelength: 790 / 808 nm Inhomogeneity: (lmax-imin) / (Imax+Imin) < 7.5 % Foto 2 22

23 Photoluminescence Results As cut wafers Solar cell (Courtesy of J. Haunschild, Fraunhofer ISE ) Good correlation between PL of as-cut wafers and solar cells Effective and cost-efficient inline analysis in solar cell production 23

24 LIMOs Application-Specific Optics Solutions Have the Following Advantages Very homogeneous light fields and spots Highest efficiency and throughput Superior manufacturing results Increased productivity and decreased cost per unit! Foto 1 Foto 1 Foto 1 24

25 2010 LIMO Lissotschenko Mikrooptik GmbH Titelfoto Thank you for your attention!