Heat Exchanger-Ingot Casting/Slicing Process. Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Silicon Solar Array Project. Fourth Quarterly Progress Report, June 19, 1976--September 24, 1976

摘要

Good seeding and growth were achieved during the past quarter with the Heat Exchanger Method at melt superheats below 10 exp 0 C. To achieve a high enough seeding temperature at low superheat, the heat exchanger was raised one inch higher in the heat zone. For this higher position, seeding conditions had to be re-established since the temperature profile across the diameter of the heat zone was flatter; i.e., the temperature in the middle of the heat zone was closer to the temperature near the heating element. All the boules produced to date have cracked during cool down, regardless of the annealing and cool-down cycle. The cracking appears to be due to the expansion mismatch between the silicon and the silica which are tenaciously bonded together. The tabulation of the heat-exchanger and furnace temperatures for this quarter's runs are presented. (ERA citation 02:019521)