Infinity Supercritical LLC


Publication Title | Structural and chemical investigations of CBD and PVD-CdS buffer layers and interfaces in Cu(In Ga) Se2-based thin film solar cells

Dewaxing Information Search

CO2 Extraction | Winterization Dewaxing | CBD and Botanical Oil Organic Fluid Extraction search was updated real-time via Filemaker on:

CO2 Extraction | Winterization Dewaxing | CBD and Botanical Oil Organic Fluid Extraction | Return to Search List

Search Completed | Title | Structural and chemical investigations of CBD and PVD-CdS buffer layers and interfaces in Cu(In Ga) Se2-based thin film solar cells
Original File Name Searched: Abou-Ras_TSF2005.pdf | Google It | Yahoo | Bing



Page Number: 001
Previous Page View | Next Page View

Text | Structural and chemical investigations of CBD and PVD-CdS buffer layers and interfaces in Cu(In Ga) Se2-based thin film solar cells | 001



Thin Solid Films 480–481 (2005) 118–123
Structural and chemical investigations of CBD- and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells
D. Abou-Rasa,b,*, G. Kostorza, A. Romeob,1, D. Rudmannb, A.N. Tiwarib,2 aETH Zu ̈rich, Institute of Applied Physics, 8093 Zu ̈rich, Switzerland
bETH Zu ̈rich, Thin Film Physics Group, Laboratory for Solid State Physics, Technoparkstrasse 1, 8005 Zu ̈rich, Switzerland Available online 8 December 2004
www.elsevier.com/locate/tsf
Abstract
It is known that high-efficiency thin film solar cells based on Cu(In,Ga)Se2 (CIGS) can be obtained using CdS buffer layers grown by chemical bath deposition (CBD). The highest efficiencies achieved with CdS buffer layers produced by physical vapor deposition (PVD) are significantly lower. To find reasons for this difference, structural and chemical properties of CBD- and PVD-CdS buffer layers and their interfaces with CIGS were investigated by means of bright-field (BF-TEM), high-resolution (HR-TEM) and energy-filtered transmission electron microscopy (EF-TEM), and also by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). PVD- CdS grains were shown to be clearly larger than the CBD-CdS grains. Also, a large defect density was detected at the PVD-CdS/CIGS interface, which is attributed to the larger lattice mismatch than at the CBD-CdS/CIGS interface. Cu diffusion from CIGS into CdS was found for the CBD- and the PVD-CdS sample. The PVD-CdS/CIGS interface turned out to be quite abrupt, whereas the CBD-CdS/CIGS interface is rather diffuse. The differences in efficiencies of solar cells with CBD- and PVD-CdS buffer layers can partly be explained by referring to the higher defect density and the probable absence of an inversion of the near-interface region from p- to n-type at the PVD-CdS/CIGS interface.
D 2004 Elsevier B.V. All rights reserved.
Keywords: Physical vapor deposition; Chemical bath deposition; CdS buffer
1. Introduction
The highest efficiencies for thin film solar cells based on a Cu(In,Ga)Se2 (CIGS) and CuInSe2 (CIS) absorber layers have been achieved using a CdS buffer layer deposited by a chemical bath deposition (CBD) process. A typical CBD solution consists of dissolved Cd2+ ions, thiourea and ammonia. Ammonia was shown to remove native oxides from the CIS surface [1].
The n-type CdS buffer layers on CIGS absorbers are used in order to form a heterojunction with the p-type CIGS and
* Corresponding author. Tel.: +41 1 633 21 26; fax: +41 1 633 11 05. E-mail address: daniel.abou-ras@phys.ethz.ch (D. Abou-Ras).
1 Now at: Universita` di Veronica, Ca ́ Vignal 2, Strada Delle Grazie, 37134 Verona, Italy.
2 Also at: Centre for Renewable Energy Systems and Technology (CREST), Department of Electronic and Electrical Engineering, Lough- borough University, Leicestershire LE11 3TU, UK.
0040-6090/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2004.11.033
to protect the CIGS surface from ion damage during ZnO/ ZnO:Al sputtering. CBD was reported to modify the surface of the CIS layer by forming an n-CdSe [1] or an n-CuInxSey [2] intermediate layer, owing to strong reaction of the Cd with the CIS absorber. Schmid et al. [3] proposed a model that includes an n-type ordered vacancy chalcopyrite (OVC) layer between CIGS and CBD-CdS. These authors detected a buried heterojunction between p-CIGS and n-OVC directly by means of electron-beam-induced current meas- urements. In contrast to these results, Kylner et al. [4] found no evidence of an intermediate compound between CIGS and CBD-CdS. The role of the CdS buffer in the p–n junction formation will be treated further below.
Although the CBD process for CdS deposition is very attractive owing to high solar conversion efficiencies, for industrial production, an in-line vacuum deposition as, e.g., physical vapor deposition (PVD), is preferred. However, the highest efficiencies achieved by PVD-CdS buffer layers hardly exceed 13%. Always (e.g., [5]), a clearly poorer

Image | Structural and chemical investigations of CBD and PVD-CdS buffer layers and interfaces in Cu(In Ga) Se2-based thin film solar cells



structural-and-chemical-investigations-cbd-and-pvd-cds-buffer-layers-and-interfaces-cuin-ga-se2-based-thin-film-solar-cells-001
Infinity Supercritical Winterization Wax Fast Filter | Filter Wax from Winterized Solution Using Infinity Supercritical Fast Filter System | CBD and Botanical Wax Filtering - Botanical Oil Wax Fast Filtering Machine- Go to website

Search Contact: greg@infinitysupercritical.com