Optimization of fabrication steps for n-type c-Si solar cells

Download

index.pdf

Date

2019

Author

Orhan, Efe

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

298
views

128
downloads

Crystalline silicon (c-Si) solar cells fabricated on p-type wafers are still dominating the photovoltaic (PV) industry due to advantages in device processing and early focus on p-type cells in the development phase of the industry. Over the years, studies on n-type Czochralski (CZ) substrates have shown that they can be more desirable for the terrestrial applications due to superior material and process advantages such as higher minority carrier lifetime, easier passivation of the surface, absence of light induced degradation (LID) and low sensibility to metallic impurities compared to p-type substrates. With these advantages, n-type CZ based c-Si solar cells with ultimate energy conversion efficiency hold a great potential in the future PV industry. The goal of this thesis is to optimize boron doping, passivation of boron emitter surface and metallization processes for fabrication of n-type c-Si solar cells. For boron doping, boron trichloride (BCl3) was used as a gas precursor with LYDOPTM system designed by SEMCO engineering. In order to obtain proper sheet resistance distribution for boron emitter during fabrication, uniformity of borosilicate glass (BSG) formation during high temperature boron diffusion was investigated. Also, most boron diffusion technologies result in the formation of an undesirable layer at the Si interface which is called as boron-rich layer (BRL). Three different methods were used for removing BRL, namely low temperature oxidation (LTO), chemical etching treatment (CET) and nitric acid oxidation of silicon (NAOS). To fabricate n-type c-Si solar cells, one side of the Si wafer should be protected by a proper masking during the diffusion process. Hence, masking property of silicon dioxide (SiO2) was investigated for boron diffusion. In addition, to increase the minority carrier lifetime by passivated boron doped surface, aluminum oxide (Al2O3) passivation and aluminum oxide/ silicon nitride (Al2O3/SiNx) stack passivation layers were deposited onto surface of the solar cells using atomic layer deposition (ALD) and plasma enhanced chemical vapor deposition (PECVD) techniques. Finally, aluminum was deposited on p+ emitter by thermal evaporation technique to obtained low contact resistance. This thesis provides useful information and contributes to research and development activities on the formation of boron emitter that is the most problematic step in the fabrication of high-efficiency n-type c-Si solar cells.

Subject Keywords

Semiconductors., Boron doping, Boron-rich layer, N-type solar cell, Passivation, Low-contact resistance.

URI

http://etd.lib.metu.edu.tr/upload/12623645/index.pdf
https://hdl.handle.net/11511/43922

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

OPTIMIZATION OF EMITTER LAYER IN N-TYPE BIFACIAL CRYSTALLINE SOLAR CELL Salimi, Yasaman; Turan, Raşit; Ünalan, Hüsnü Emrah; Department of Micro and Nanotechnology (2022-5-09) P-type solar cells currently hold most of the market share in industrial solar cell fabrication statistics. NREL's highest efficiency record for p-type crystalline perc cells is 22.8%. However, there is an ever-increasing interest in n-type wafers due to the many advantages they have against p-type cells. According to the ITRPV's estimation, the n-type cell structures will be taking half the industry's share by 2031. Compared to p-type cells, n-type cells yield better efficiency and lifetime values and are ...
Analysis of boron doped hydrogenated amorphous silicon carbide thin film for silicon heterojunction solar cells Salimi, Arghavan; Turan, Raşit; Department of Micro and Nanotechnology (2019) Silicon based solar cells are the dominant type of solar cells in the photovoltaic industry. Recently, there have been increasing efforts to develop c-Si solar cells with higher efficiency and lower cost. Among them, silicon heterojunction solar cell (SHJ) is attracting much attention because of its superior performance values demonstrated at both R&D and industrial levels. One of the common limiting criteria is the recombination at the front side which can be solved by providing proper passivation at the f...
INVESTIGATION OF SCREEN-PRINTED AND EVAPORATED METAL CONTACTS ON BORON IMPLANTED EMITTER Özmen, Ege; Turan, Raşit; Kocaman, Serdar; Department of Micro and Nanotechnology (2021-8-27) Due to advantages in device manufacturing and the low cost of ownership, crystalline silicon (c-Si) solar cells fabricated on p-type wafers continue to dominate the photovoltaic (PV) market. Studies on n-type Czochralski (CZ) substrates have shown that they are more desirable for terrestrial applications than p-type substrates due to superior material and performance advantages such as higher minority carrier lifetime and easier surface passivation, absence of light-induced degradation (LID), and low sensit...
Improvement of silicon heterojunction solar cell performance with new surface structure and wide band gap carrier selective layers Dönerçark, Ergi; Turan, Raşit; Yerci, Selçuk; Department of Micro and Nanotechnology (2021-10-15) The photovoltaic (PV) industry is dominated by silicon-based solar cells owing to the abundance of silicon and its full-fledged technology. The main road for the PV industry points out to enhance the conversion efficiency of solar cells while decreasing production costs, which is crucial for improving renewable energy market share. The silicon heterojunction solar cells (SHJ) are receiving attention on this road map due to their higher conversion efficiencies, simple process flow, and low-temperature fabric...
Simulation of an efficient silicon heterostructure solar cell concept featuring molybdenum oxide carrier-selective contact MEHMOOD, Haris; NASSER, Hisham; Tauqeer, Tauseef; HUSSAIN, Shahzad; Ozkol, Engin; Turan, Raşit (2018-03-25) Transition metal oxides/silicon heterocontact solar cells are the subject of intense research efforts owing to their simpler processing steps and reduced parasitic absorption as compared with the traditional silicon heterostructure counterparts. Recently, molybdenum oxide (MoOx, x<3) has emerged as an integral transition metal oxide for crystalline silicon (cSi)-based solar cell based on carrier-selective contacts (CSCs). In this paper, we physically modelled the CSC-based cSi solar cell featuring MoOx/intr...

Citation Formats

E. Orhan, “Optimization of fabrication steps for n-type c-Si solar cells,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Metallurgical and Materials Engineering., Middle East Technical University, 2019.