Browse Prior Art Database

Zone Levelling Control System

IP.com Disclosure Number: IPCOM000098658D
Original Publication Date: 1959-Aug-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Smith, RR: AUTHOR

Abstract

The control system automatically maintains substantially constant the width of the molten zone 10 in a germanium rod 11 that is being zone levelled. The apparatus includes an outer quartz tube 12 having a radio-frequency heater coil 13 disposed around a portion of it and an inner quartz tube 14 which has limited axial adjustment with respect to the tube 12. Tube 14 carries a carbon ring 15 which establishes the narrow molten zone 10 in the germanium rod 11 when the coil 13 is energized. The rod 11 is disposed in a conventional quartz boat (not shown) which pulls the rod through the tube 12 and shifts the position of the molten zone 10 along the rod.

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Zone Levelling Control System

The control system automatically maintains substantially constant the width of the molten zone 10 in a germanium rod 11 that is being zone levelled. The apparatus includes an outer quartz tube 12 having a radio-frequency heater coil 13 disposed around a portion of it and an inner quartz tube 14 which has limited axial adjustment with respect to the tube 12. Tube 14 carries a carbon ring 15 which establishes the narrow molten zone 10 in the germanium rod 11 when the coil 13 is energized. The rod 11 is disposed in a conventional quartz boat (not shown) which pulls the rod through the tube 12 and shifts the position of the molten zone 10 along the rod.

A sapphire rod 16, responsive to infrared radiation from a liquid solid interface 17 of the molten zone 10, is connected through a thermopile 18 to a control unit 19 which varies the power supplied by a radio frequency generator 20 to the coil 13. A second sapphire rod 21 is

arranged to respond to radiation from the other liquid-solid interface 25 of the molten zone 10 and is connected through a thermopile 26 and a detector- amplifier 27 to a servo-mechanism 28. The latter is operatively connected by a conventional coupling means, represented by the broken line 29, to the inner tube 14 to effect minor adjustments of the carbon ring 15 relative to the coil 13 which modifies the position of the interface 25.

The control effects, developed by the sapphire rods sensing the positions of the in...