| 摘要 |
1286063 High resistance gallium arsenide SIEMENS AG 12 Jan 1970 [11 Jan 1969] 1355/70 Heading C1A Arsenic vapour is introduced into the synthesis vessel in the manufacture of high resistance gallium arsenide by horizontal two temperature process through a molten layer of boron oxide at a temperature between 600‹ and 750‹ C. The boron oxide layer is between 0À1 and 2 cm. thick or more. The process may be carried out in either open or closed vessels. In the former case an inert carrier gas, e.g. argon, is necessary to conduct arsenic through the boron oxide layer. In an example, 20 gm. of gallium are placed in section A of a synthesis ampoule as shown in Fig. 2 at 28, and the section A is then sealed at 29 under high vacuum, 25 being a frangible diaphragm. Boron trioxide, which has been dried is introduced, to 24, in section B of the synthesis ampoule in the form of small fragments, whilst the stoichiometric quantity of arsenic 23 required to form gallium arsenide is introduced via 22. A and B are fused together at F and the entire volume evacuated up to 25, after which sealing at 22 is carried out. Heating is carried out in a tubular furnace such that sections D and E of the ampoule reach 620‹ C. and then section C is brought to the same temperature. Arsenic vapour diffuses through B 2 O 3 , 34, past staggered baffles 36 and condenses at G in the synthesis ampoule. When all the arsenic has sublimed from 33 to G the ampoule is sealed at 37. The ampoule is heated in a two-temperature furnace so that gallium is at 1250‹ C. and arsenic at 620‹ C. The frangible diaphragm is then broken and arsenic vapour reacts with the gallium to form gallium arsenide which is crystallized by controlled solidification. |
