Process development and comparison of various boron emitter technologies for high-efficiency (~21%) n-type silicon solar cells

Lee

Progress in Photovoltaics

et al. 2019

This study proposes a hybrid solar cell structure for a highly efficient silicon solar cell obtained by combining two passivating contact structures, namely, a heterojunction and polysilicon passivating contact. Given that the major cause of the loss in efficiency of crystalline silicon solar cells is carrier recombination at the metal‐semiconductor junction, a passivating contact having high‐quality passivation and a low contact resistance was introduced. In this study, two major passivating contact solar cells were combined. By applying an intrinsic thin amorphous silicon layer at the front and a tunneling oxide at the rear, a hybrid silicon solar cell with an efficiency of 21.8% was fabricated. Moreover, to evaluate the potential efficiency limit and to suggest methods for improving the cell performance of the proposed amorphous silicon emitter tunnel oxide back contact structure, the cell efficiency was simulated, and the result indicated that an efficiency of 26% could be achieved by controlling the thickness and resistivity of the wafer.

Section: Introductionmentioning

confidence: 99%

Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts

Lee

Progress in Photovoltaics

et al. 2019

Progress in Photovoltaics

“…High photovoltaic (PV) conversion efficiencies can be reached by this way with recently 20.8% obtained on a pilot line of screen‐printed n‐type PERT (n‐PERT) solar cells . However, a keen interest toward single‐side doping techniques has been seen these past few years . Compared with the double‐side doping of the BBr 3 and BCl 3 diffusions, they can strongly simplify the solar cells process flows and thus reduce the production cost of solar cells with boron‐doped layers.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with the double‐side doping of the BBr 3 and BCl 3 diffusions, they can strongly simplify the solar cells process flows and thus reduce the production cost of solar cells with boron‐doped layers. Most of them have demonstrated high boron emitter electrical qualities such as spin‐on coating, screen printing, codiffusion from atmospheric pressure chemical vapor deposition (APCVD) of doped layers, and ion implantation . Some of these single‐side doping techniques are already used in high‐efficiency n‐type solar cells …”

Section: Introductionmentioning

confidence: 99%

“…3 However, a keen interest toward singleside doping techniques has been seen these past few years. 4 Compared with the double-side doping of the BBr 3 and BCl 3 diffusions, they can strongly simplify the solar cells process flows and thus reduce the production cost of solar cells with boron-doped layers. Most of them have demonstrated high boron emitter electrical qualities such as spin-on coating, 5 screen printing, 4 codiffusion from atmospheric pressure chemical vapor deposition (APCVD) of doped layers, 6 and ion implantation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plasma‐immersion ion implantation: A path to lower the annealing temperature of implanted boron emitters and simplify PERT solar cell processing

Lanterne

Desrues

Lorfeuvre

et al. 2019

Ion implantation is a suitable and promising solution for the massive industrialization of boron doping, which is a crucial process step for most next‐generation solar cells based on crystalline silicon (c‐Si). However, the use of ion implantation for boron doping is limited by the high temperature (in the 1050°C range) of the subsequent activation anneal, which is essential to dissolve the boron clusters and reach a high‐emitter quality. In this work, we propose the use of plasma‐immersion ion implantation (PIII) from B2H6 gas precursor instead of the standard beamline ion implantation (BLII) technique to decrease this temperature down to 950°C. PIII and BLII boron emitters were compared with annealing temperatures ranging from 950°C to 1050°C. Contrary to BLII, no degradation of the emitter quality was observed with PIII implants annealed at 950°C along with a full activation of the dopants in the emitter. At 1000°C, emitter saturation current densities (J0e) below 21 fA/cm2 were obtained using the PIII technique regardless of the tested implantation doses for sheet resistances between 110 and 160 Ω/sq. After metallization steps, the metal/emitter contact resistances were assessed, indicating that these emitters were compatible with a conventional metallization by screen‐printing/firing. The PIII boron emitters' performances were further tested with their integration in n‐type passivated emitter rear totally diffused (PERT) solar cells fully doped by PIII. Promising results already show a conversion efficiency of 20.8% using a lower annealing temperature than with BLII and a reduced production cost.

Journal of the Korean Institute of Electrical and Electronic Ma

“…이처럼 우수한 웨이퍼 품질과 inactive doping의 차이에 의한 boron diffusion layer의 낮은 saturation current density (J 0e )는 N-type 태양전지의 장점이다 [4]. 하지만 이러한 장점에도 불구하고 boron diffusion layer의 형성, passivation에 연관된 기술적 도전과 비용 때문에 P-type 실리콘 태양전지가 주류를 이루고 있으며 다양 한 boron diffusion 기술들이 현재까지 조사 및 사용 되고 있지만 뚜렷하게 우위에 있는 기술은 나오고 있 지 않은 상황이다 [5]. …”

unclassified

Boron Diffused Layer Formation Process and Characteristics for High Efficiency N-type Crystalline Silicon Solar Cell Applications

Shim¹,

Park²,

Yi³

2017

N-type crystalline silicon solar cells have high metal impurity tolerance and higher minority carrier lifetime that increases conversion efficiency. However, junction quality between the boron diffused layer and the n-type substrate is more important for increased efficiency. In this paper, the current status and prospects for boron diffused layers in N-type crystalline silicon solar cell applications are described. Boron diffused layer formation methods (thermal diffusion and co-diffusion using a-SiO X :B), boron rich layer (BRL) and boron silicate glass (BSG) reactions, and analysis of the effects to improve junction characteristics are discussed. In-situ oxidation is performed to remove the boron rich layer. The oxidation process after diffusion shows a lower B-O peak than before the Oxidation process was changed into SiO 2 phase by FTIR and BRL. The a-SiO X :B layer is deposited by PECVD using SiH 4 , B 2 H 6 , H 2 , CO 2 gases in N-type wafer and annealed by thermal tube furnace for performing the P+ layer. MCLT (minority carrier lifetime) is improved by increasing SiH 4 and B 2 H 6 . When a-SiO X :B is removed, the Si-O peak decreases and the B-H peak declines a little, but MCLT is improved by hydrogen passivated inactive boron atoms. In this paper, we focused on the boron emitter for N-type crystalline solar cells.