4 Ningbo Institute of Industrial Technology, CAS-Baojie Yan
Thin Oxide/poly-Si Passivation in High Efficiency c-Si Solar Cell and Manufacturing Perspective Baojie Yan (闫宝杰） Yuheng Zeng (曾俞衡） Jichun Ye (叶继春） Ningbo Institute of Materials Technology & Engineering, CAS China Ningbo Institute of Industrial Technology (CNITECH) 1/101 太阳能及光电子器件研究团队 Outline ◆Introduction (skipped) ◆R&D Study in our group • Progress in the SiOx/poly-Si passivation • Solar cell fabrication and optimization • A few industrial viable process developments • Collaboration with industrialization partners ◆Summary 2 太阳能及光电子器件研究团队 Terminology ◆In the Literature • Fraunhofer: TOPCon (Tunnel Oxide Passivated Contact) • ECN/TNO: PERPoly (Passivated Emitter Rear PolySi) • ISFH: POLO (Polycrystalline Silicon on Oxide) • SERIS/Meyer Burger: monoPolyTM (monofacial application of a Polysilicon layer) ◆Our Proposal and Registered Trade Mark (TM) ✓ PerTOPTM (Passivated emitter and rear Thin Oxide/Poly-Si Passivation) • Belongs to PERX’s family, and could be used for upgrade PERX line • Credit to TOPCon, and avoid using tunneling (pin holes?) • Being registered and to be used for the Trade Mark for our future product 3 太阳能及光电子器件研究团队 Solar Cell Structure 4 The PerTOPTM Solar Cell Structure Whole back area metallization Bifacial Solar Cell The same as n-PERT The new parts 太阳能及光电子器件研究团队 The Major Work in Our Group • Acidic Solution: HNO3(110C), HNO3+HSO4 (60C) • Gas Process: N2O PECVD, and O2 thermal oxidization SiOx fabrication • Parallel Plate PECVD • Tube PECVD a-Si:H fabrication • Regular Thermal Annealing (780-940C) • Rapid Thermal Process (RTP)Crystallization Hydrogenation • Forming Gas Annealing (FGA) • SiNx:H or AlOx:H Capping and Annealing • Moisture Annealing (innovative, patented) Key Elements and Process 5 太阳能及光电子器件研究团队 6 ✓ J0,min= 2 fA/cm2, ✓ ρc=5 mΩcm2 ✓ iVoc= 721 mV (w/o post-treatment) ✓ iVoc= 747 mV (post-treatment) Solar grade CZ wafer The Key Progress in Our Group Champion: J0,single-side=1.9 fA/cm2, , τ=8.0 ms (Δn=11015cm-3) iVoc=747 mV, iFF=86.3% (Transient mode) 太阳能及光电子器件研究团队 7 The Key Progress in Our Group: Progress of p-TOPCon p-Poly-Si ✓ J0,min= 14 fA/cm2(as-annealed)✓ J 0,min= 6.2 fA/cm2 (Al2O3 capping) ✓ iVoc= 708 mV (as-annealed) ✓ iVoc= 720 mV (Al2O3 capping) Solar grade n-CZ wafer Champion: J0,single-side=6.2 fA/cm2, , τ=2.4 ms (Δn=1e15cm-3) iVoc=720 mV, iFF=83.8% (Transient mode) 太阳能及光电子器件研究团队 8 Lab: 22.1 % (2cm× 2cm) (in-house efficiency) ✓ Next goal: 22.5% Processes Texture Borondiffusion Polish Tunnel oxide Polysilicon Crystallization Passivation CharacterizationMetallization The Key Progress in Our Group 太阳能及光电子器件研究团队 9 The Key Progress in Our Group 0 20 40 60 80 100 300 500 700 900 1100 EQE of n-type TOPCon solar cell Wavelength (nm) Comment Uoc (V) Isc (A) FF (%) Eta (%) Champion cell 668.6 9.753 80.65 21.53 ◆ 6 inch CZ solar grade n-c-Si 0.5~2 .cm, 180 μm ◆ Passivation of large-size wafer： 716~721 mV ◆ Lab + Company: 21.53% (Rear passivation was made in our lab, front AlOx+SiNx and metallization in our industrial partner) 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 TOPCon (15.6cm× 15.6cm) Voc 668.6 mV Isc 9.753 A (39.95 mA/cm2) FF 80.65% Eff 21.53% 太阳能及光电子器件研究团队 10 Plasma assisted N2O PECVD oxidation process Si-substrateSi-substrate Plasma N2O ultra-thin SiOx n-type Si substrate P-doped polysilicon The Key Industrial Viable Process 太阳能及光电子器件研究团队 11 n-type Si substrate P-doped polysilicon Apply the N2O-SiOx to p-type Si wafer (1 Ω-cm) (LONGi) ✓ iVoc=730 mV ✓ J0= 4.1 fA/cm2 ✓ =800 s (Δn=1× 1015 cm-3) iVoc=742 mV J0 =3.0 fA/cm2 τ=~1050 μs (Δn=1× 1015 cm-3) Al2O3 capping Surface passivation for p-type wafer Solar Energy Materials and Solar Cells 200 (2019) 109926 The Key Industrial Viable Process 太阳能及光电子器件研究团队 Hydrogenation by Moisture Annealing (Patented and accepted by Solar RRL) ✓ Simple ✓ Effective ✓ Reliable The Key Industrial Viable Process Solar RRL, minor revision 12 太阳能及光电子器件研究团队 The PECVD Manufacturing Approach Surf. Prep. Key Step Front Pass Metal Cont. 1. Cleaning 2. Texturing 3. B Diffusion 4. Back Polishing 1. N2O PECVD or Thermal Oxidization 2. PECVD (Tube or Parallel Plate) 3. Thermal or FTA, or Others 4. SiNx:H + Annealing (bifacial) or Moisture Annealing (whole area) 1. Front Al2O3 2. Front SiNx:H 3. Rear SiOx:H for bifacial 1. Screen Print and Firing on both side 2. Test 1. No or little wrapping around coating 2. Shorter process time with less steps 3. In-situ doping 4. p-Poly-Si capable for PERC upgrade Pros: Cons: 1. Parallel Plate PECVD machine costy 2. Additional issues with tube PECVD needed to be resolved 3. Powder formation in PECVD system 13 太阳能及光电子器件研究团队 Collaboration with Industrial Partners With Changzhou Shichuang Energy (SCenergy) Technology Co. 常州时创能源技术公司 ✓ Retrofired a Tube PECVD system ✓ Developed SiOx and poly-Si fabrication process for making the rear SiOx/n-poly-Si passivation contact ✓ Resolved many technique issues ✓ Have been in the process of making large area cell fabrication 14 太阳能及光电子器件研究团队 Location Zone Lifetime (s) (@1101 cm-3) J0,s(fA/cm2) (@31015 cm-3) iVoc (mV) Location Zone Lifetime (s) (@11015 cm-3) J0,s(fA/cm2) (@31015 cm-3) iVoc (mV) 1# 4403 7.8 724 6# 3479 10.5 721 2# 10265 2.4 738 7# 3129 11.9 719 3# 8878 3.5 734 8# 7734 3.6 733 4# 12962 2.0 741 9# 13102 1.9 743 5# 12405 2.3 741 10# 13933 1.9 742 With Industrial Partner: SCerengy (时创 ) 15 Tube PECVD (416 piece, 6-inch CZ solar grade wafer/tube） : n-poly-Si on n-c-Si wafer with no hydrogenation 太阳能及光电子器件研究团队 Collaboration with Industrial Partners With Ideal Energy (Shanghai) Sunflower Thin Film Equipment Ltd. 上海理想万里晖薄膜设备 有限公司 ✓ Explored the RF and VHF parallel plate PECVD system ✓ Developed SiOx and poly-Si fabrication process for making the rear SiOx/n-poly-Si passivation contact ✓ Primary results show a great promising ✓ Have been in the process of optimizing the passivation quality and evaluating the feasibility of the existing machines and the modification of PECVD systems. 16 太阳能及光电子器件研究团队 Sample Lifetime (s)(11015 cm-3) J0,s(fA/cm2) (31015 cm-3) iVoc(mV) 1 1-1 4477 3.5 7381-2 2362 6.2 731 2 2-1 5676 2.9 7412-2 5165 3.1 738 3 3-1 5318 2.5 7403-2 8804 2.6 742 4 4-1 10078 2.5 7404-2 6549 5.3 736 Parallel Plate PECVD Large-Area Manufacturing Machine with VHF at high Rate SiOx/n- poly-Si on 6 inch solar grade CZ n-c-Si, without hydrogenation With Industrial Partner（理想万里晖） 17 太阳能及光电子器件研究团队 Parallel Plate PECVD Large-Area Manufacturing Machine with RF deposited SiOx/n-poly-Si on 6 inch solar grade CZ n-c-Si, without hydrogenation Run # Sample # Lifetime (s) （ 1.0× 1015cm-3） J0,s(fA/cm2) (31015 cm-3) iVoc (mv) Run# Sample # Lifetime (s) （ 1.0× 1015cm-3） J0,s(fA/cm2) (31015 cm-3) iVoc (mv) N#1 1 4219 6.6 731 N#13 1 7053 3.3 7432 4333 7.0 731 2 7249 3.9 738 N#6 1 8916 2.5 743 N#17 1 7572 3.0 7412 8225 2.5 742 2 7015 3.1 741 N#9 1 6438 3.4 7412 7166 3.5 740 With Industrial Partner（理想万里晖） 18 太阳能及光电子器件研究团队 Summary ➢ Reviewed the progress made in our group ➢ Showed the major passivation and solar cell results achieved in our lab ➢ Provided a few industrial viable fabrication processes ➢ Showed our proposal for the industrialization approach ➢ Presented some preliminary but promising results from our industrial partner’s manufacturing PECVD machines 19 太阳能及光电子器件研究团队 Summary THE TAKING HOME MESSAGE: ✓ CNITECH (宁波材料所 ) has gone through the PerTOPTM cell fabrication process ✓ They are collaborating with SCenergy developing the TUBE PECVD process ✓ They are collaborating with Ideal Energy developing the PARALLEL PLATE PECVD process 20 太阳能及光电子器件研究团队 Acknowledgment Jichun Ye 叶继春 Yuheng Zeng 曾俞衡 Mingdun Liao 廖明墩 AND Graduate students AND SCenergy (时创 ): Liming Fu (符黎明 ), Yuhong Cao (曹育红 ), Xijia Luo (罗西佳 ) Ideal Energy (理想万里晖 ): Bony Ma (马哲国 ), Kejun Wu(吴科俊 ), Qian Geng (耿茜） 21 太阳能及光电子器件研究团队 Acknowledgment Thank You for Your Attention and Welcome for Collaborations and ??? 22
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