Quarzglasrohr mit UEberzug

摘要

1,255,551. Diffusion into semi-conductors. HERAEUS - SCHOTT QUARZSCHMELZE G.m.b.H. 25 March, 1969 [30 March, 1968], No. 15639/69. Heading H1K. [Also in Division C1] A fused silica tube capable of being subjected to temperatures in excess of 1000‹ C., particularly for use in the doping of semi-conductor crystals therein by diffusion techniques, has, at least in that part of the tube to be subjected to such temperatures, a coating consisting of a continuous fine layer (2) of crystalline silica, e.g. cristobalite, which has a thickness less than 5% of the wall thickness of the fused silica tube (1) in the region of the coating. Preferably the layer thickness is less than 1%. A protective layer (3) over layer (2) may consist of germanium oxide, a mixture of germanium and silicon oxides or of a mixed glass, the layer (3) becoming plastic at approximately 1300‹ C. The layer (2) may be formed by spraying a very fine, pure, cristobalite in powder form on to the tube (1) and heating in a flame or in a furnace at a high temperature.