摘要:

In 1997, a new 4 year plan was initiated in order to achieve more specific goals by FY 2000. An outline of the new 4 year program will be discussed with emphasis on Si thin film solar cells. The main objective of the program is to achieve stabilized efficiencies of over 10&percent; for large area a-Si based solar cell modules. In addition to amorphous Si based materials, polycrystalline and single crystal thin film Si has attracted attention as a low-cost solar cell material, where the target is to achieve 13-15&percent; efficiencies. Material and processing issues in the area of Si thin film solar cells will be briefly reviewed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57953

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A new microscopic and kinetic model of light-induced metastability in hydrogenated amorphous silicon (a-Si:H) was recently proposed. Carrier recombination excites H from deep Si-H bonds into a mobile configuration, leaving a threefold-coordinated Si dangling bond (DB) defect at the site of excitation—a process long suspected to be an element of metastable DB production. Normally, mobile H are recaptured at DB defects and neither metastability nor net DB production results. However, when two mobile H collide, they form a metastable two-hydrogen complex and leave two-spatially-uncorrelated Staebler-Wronski DBs. The model leads to differential equations describing the evolution of the mobile H and DB densities and a variety of new predictions. New directions for improving the stability of a-Si:H are discussed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57955

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We review the continuing improvements in amorphous, microcrystalline and thin film crystalline Si materials and devices over the past few years. Many of these improvements have resulted from asking fundamental questions regarding how the material is grown, what its structure is, and how to make it better. For amorphous materials, significant changes in growth chemistry have resulted in reductions in H content in some cases, changes in localized H bonding, changes in microstructure, and in reductions in microstructural voids in the material, thereby leading to improved stability and performance. By achieving a transition from amorphous to microcrystalline phase, it has been possible to make high quality, small grained crystalline Si films with naturally passivated grain boundaries. The high quality of microcrystalline films have allowed one to make high performance solar cells in these materials. Finally, the achievement of super-back reflectors and growth of high quality thin film crystalline Si films on these back reflectors have resulted in the achievement of thin film Si solar cells exceeding 10&percent; conversion efficiency. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57947

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A triple-junction amorphous silicon alloy production facility was commissioned by United Solar Systems Corp. in March 1997. The plant has been producing a variety of products for applications ranging from remote power to grid-connected systems. The products have gone through stringent qualification tests, and are winning recognition from customers and many outside agencies. In this paper, we discuss the manufacturing issues that were addressed to design the plant, the plant performance, and future plans. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57956

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

R & D on amorphous silicon based tandem junction devices has improved the throughtput, the material utilization, and the performance of devices on commercial tin oxide coated glass. The tandem junction technology has been scaled-up to produce8.6&hthinsp;Ft2monolithically integrated modules in manufacturing at the TF1 plant. Optimization of performance and stability of these modules is ongoing. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57954

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A novel, non-vacuum technique based on nano-particle deposition has been developed for the formation of CIS-type solar cell absorbers. Solar cells with >12&percent; efficiency were previously demonstrated using this technique. Improvements in module integration processes have recently yielded 8&percent; minimodules of 75 cm2area. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57957

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The built-in electric field in polycrystallineCuInSe2(CIS) near gold co-planar contacts was quantitatively revealed for the first time by the photomixing technique. A He-Ne laser beam was focused locally on the CIS sample near one of its contact. While both dc dark and photo-currents showed ohmic behavior, the high frequency ac current was non-zero for zero applied dc bias, which reveals a built-in electric field of ∼1000V/cm. The capability of the photomixing technique to probe local charge transport properties is expected to be very useful for, e.g., the quantitative evaluation of the quality of ohmic contacts and the investigation of electric field induced p-n junction formation in CIS and related materials. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57893

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Thin film CdS has been widely used in thin-film photovoltaic devices. The most efficientCu(In,&hthinsp;Ga)Se2(CIGS) solar cells reported to date utilized a thin CdS buffer layer prepared by a reactive solution growth technique known as chemical bath deposition (CBD). Considerable effort has been directed to better understand the role and find a replacement for the CBD CdS process in CIGS-based solar cells. We reported a low temperature (∼150&hthinsp;°C) Metalorganic Chemical Vapor Deposition (MOCVD) CdS thin film buffer layer process for CIGS absorbers. Many prior studies have reported that CBD CdS contains a mixture of crystal structures. Recent investigations of CBD CdS thin films by ellipsometry suggested a multilayer structure. In this study we compare CdS thin films prepared by CBD and MOCVD and the effects of annealing. TED and XRD are used to characterize the crystal structure, the film microstructure is studied by HRTEM, and the optical properties are studied by Raman and spectrophotometry. All of these characterization techniques reveal superior crystalline film quality for CdS films grown by MOCVD compared to those grown by CBD. Dual Beam Optical Modulation (DBOM) studies showed that the MOCVD and CBD CdS buffer layer processes have nearly the same effect on CIGS absorbers when combined with a cadmium partial electrolyte aqueous dip. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57958

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Solar cells have been made from uniformCu(In,&hthinsp;Ga)Se2films deposited by elemental evaporation with two different Ga compositions,Ga/[In+Ga]=0.30and 0.65. The solar cells fabricated from these uniform films have 15&percent; efficiency forGa/[In+Ga]=0.30,but the device efficiency is less than expected for the high Ga content due primarily to a decrease in fill factor and open circuit voltage. Analysis of current-voltage results have shown that the main cause of this decrease is a voltage dependent light generated current,JL,(V).Devices were fabricated with both standard (1 &mgr;m) and semi-transparent (0.04 &mgr;m) Mo contacts. Bi-facial spectral response measurements were made and analyzed on the devices with the semi-transparent Mo contacts in order to determine the changes in collection efficiency as a function of changing Ga composition and applied voltage. This analysis determined that the decrease in the light generated current with increasing voltage is primarily due to a reduction in minority carrier diffusion length, L, from about 0.8 to 0.1 &mgr;m. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57959

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Junction formation inCuInSe2(CIS) has been studied by exposing thin films and single-crystal samples to solutions containingNH4OHandCdSO4.The treated samples were analyzed by secondary ion mass spectrometry to determine the amount and distribution of Cd deposited on the surface of the films. Cadmium is found to react with the surface for all the solution exposure times and temperatures studied. The reaction rapidly approaches the endpoint and remains relatively unchanged for subsequent solution exposure. Cadmium in-diffusion, as measured by secondary ion mass spectrometry, is obscured by topography effects in the thin-film samples and by ion-beam mixing and topography in the single-crystal sample. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57894

出版商:AIP    

年代:1999

数据来源: AIP