Gerhard Hoyler

Fast Si sheet growth by the horizontal supported web technique

Abstract The horizontal supported web (HSW) technique was developed for the high-throughput production of sheet silicon for low-cost crystalline solar cells. The crystallization of sheet Si is brought about by pulling a carbon fibre net horizontally across the surface of an Si melt at a temperature near the melting point. The sheet grows in thickness for as long as it remains in contact with the melt, its final thickness depending on the length of the melt and the pulling speed. Pulling speeds of 1 m/min have so far been reached for sheets 6 cm in width and thicknesses between 300 and 600 It m. Electrical measurements performed on the first solar cells showed that a cell efficiency of 9% was obtained with such a supported web (SW) material.

Low Cost High Speed Si Ribbon Growth by the HSW-Technique

The development of the Horizontal Supported Web (HSW) technique for growth of Si ribbon material for solar cells has been continued. The dependence of the pulling speed on the melt length was calculated and the influence of the temperature gradient in the melt investigated. In present experiments a pulling speed of 1 m/min is used requiring a melt length of about 20 cm. At this speed the continuous growth of ribbons several meters long, 6 cm wide and 0.6 mm thick has been obtained. Test solar cells 2 cm x 2 cm in size have an efficiency of η = 11%. The cost per Watt-area were estimated for different production rates and conditions; at 6 MW/ a the cost comes down to 0.40 Dollar/Watt-area.

Voltage Multiplier with Integrated Metalized Capacitor Network

A newly developed voltage multiplier which generates high voltage for cathode-ray tubes embodies, in addition to silicon diodes, an integrated network of some 30 000 self-healing capacitors arranged in parallel and in series. This network is sawed by means of a special technique from a large ring-shaped mother capacitor into rectangular blocks. The principal advantages of this method of fabrication are, first, that the internal series circuit results in relatively low field strength in the region of the electrode edges and, second, that the dissipation of self-healing energy due to dielectric breakdowns is limited. These advantages, together with the easy handling of the precise geometric configurations, have made it possible to implement a new device in which small cubic volume and extremely low voltage drops during self-healing are accompanied by excellent reliability.