Silicon web process development. Quarterly report, July 1-September 30, 1979

Technical Report · Mon Jan 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/5649273· OSTI ID:5649273

Duncan, C S; Seidensticker, R; Hopkins, R H; McHugh, J P; Hill, F E; Skutch, M E; Driggers, J M

We have recently produced the widest silicon web crystal 47mm, and demonstrated the highest web area output rate to date, 27cm/sup 2//min. The latter result is particularly significant. Web growth at this rate sustained by means of Melt replenishment for prolonged periods produces a projected web wafer cost (including polysilicon) about equal to the JPL 1986 sheet cost objective even if $25/kg silicon is used for feedstock. When $10/kg silicon becomes available the projected web wafer cost falls significantly below the JPL cost goal. Melt replenishment technology development is thus a key requirement for the web process. Recently we demonstrated five hours of simultaneous web growth from a melt replenished by silicon pellets injected at a controlled rate. This is more than double the previous best result. A laser melt level sensor required to monitor melt position for closed loop control of the replenishment rate has been designed. The components have been procured, and the sub system is now in final assembly stages. Direct measurements of web system temperatures coupled with determinations of web growth parameters have been used to verify the computer model developed for the web process. This tool can now be used with some confidence to guide the design of system components to improve web area output rates. We have also verified the correlation between cell performance predicted from 1cm/sup 2/ diagnostic solar cells and larger area devices made on web. Cell efficiencies of 12 to 14% are typical even for experimental crystals produced under unoptimized growth conditions.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
• DOE Contract Number: NAS-7-100-954654
• OSTI ID: 5649273
• Report Number(s): DOE/JPL/954654-9
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
CRYSTAL GROWTH
CRYSTAL GROWTH METHODS
CRYSTALS
DENDRITIC WEB GROWTH METHOD
ELEMENTS
EQUIPMENT
EVALUATION
FURNACES
MEASURING INSTRUMENTS
MELTING
MONITORING
MONOCRYSTALS
PHASE TRANSFORMATIONS
RESEARCH PROGRAMS
SEMIMETALS
SILICON
TEMPERATURE MONITORING
THICKNESS GAGES