DocumentCode :
3520473
Title :
Value of thermal oxide for ion implant based c-Si solar cells
Author :
Bhosle, Vikram ; Dubé, Christopher E. ; Bateman, Nick
Author_Institution :
Appl. Mater., Varian Semicond. Equip., Gloucester, MA, USA
fYear :
2012
fDate :
3-8 June 2012
Abstract :
In this paper we present the improvements in cell performance for ion implanted C-Si solar cells by thermal oxidation. We have investigated the effect of oxidation on cell efficiency (CE) and systematically evaluated the effect of oxide thickness on emitter quality for the ion implanted emitters. It is shown that the CE of ion implanted cells increases by ~0.3% absolute with increase in oxide thickness and is attributed to lower J0e. Additionally, the effect of oxidation on dopant profile of these emitters is also characterized using sheet rho (Rsheet) measurements and SIMS analysis, which demonstrate that an optimal profile can be achieved with a single step anneal/oxidation of the ion implanted emitters. The lower J0e achieved for the ion implanted emitters with an oxide layer (10-30nm) is due to superior passivation quality of the thermal oxide and the optimized dopant profile. It is to be noted here that the thermal oxidation is part of the post implant anneal and does not lead to excessive drive in and allows controlling the dopant profile/junction depth (xj) very precisely. This unique ion implant based process flow also offers a distinct advantage over two step diffusion process(es) (POCl3 → PSG etch → high temperature thermal oxidation) which are required to passivate emitters fabricated using POCl3 with a thermal oxide. Thus, the proposed approach of single step anneal/oxidation of ion implanted emitters offers an attractive solution for passivating surfaces and manufacturing high efficiency solar cells with advanced architectures.
Keywords :
annealing; elemental semiconductors; ion implantation; optimisation; oxidation; passivation; semiconductor junctions; silicon; solar cells; SIMS analysis; Si; cell efficiency; diffusion process; dopant profile optimization; implant annealing; ion implanted cell; ion implanted emitter; junction depth control; passivate emitter; passivation quality; sheet rho measurement; solar cell; thermal oxidation; Annealing; Doping profiles; Implants; Oxidation; Passivation; Photovoltaic cells; Silicon; ion implant; oxide; passivation; photovoltaic cells; saturation current density; silicon;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE
Conference_Location :
Austin, TX
ISSN :
0160-8371
Print_ISBN :
978-1-4673-0064-3
Type :
conf
DOI :
10.1109/PVSC.2012.6318017
Filename :
6318017
Link To Document :
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