Aufwachsschichten aus halbleitenden Verbindungen,hergestellt nach einem Verfahren der Schmelzepitaxie

1,255,576. Making semi-conductor structures. SIEMENS A.G. 18 Feb., 1970 [19 Feb., 1969], No. 7704/70. Heading H1K. The components 5 for a silicon-doped gallium arsenide melt are placed in a silica or carbon capsule on the end of which is an N-type gallium arsenide substrate 4 secured by the threaded cap 2. The capsule is placed in a silicon ampoule 1 which is evacuated and sealed so that the subsequent preparation of the melt and a deposition process may be carried out in an oxygen-free atmosphere formed (mainly) by the vapour from the heated gallium arsenide. The melt components are fused at 970‹ C. and the ampoule inverted to deposit the melt on the substrate and the assembly allowed to cool. Silicon is an amphoteric dopant in gallium arsenide and the material deposited with a melt temperature above 920‹ C. is N-type but later growth is P-type. Deposition is stopped by again inverting the ampoule when the melt temperature has fallen to 500‹ C. The melt may be reheated and the process repeated to form an alternating sequence of N-type and P-type layers on the initial substrate. The conditions are chosen to be such that the deposited gallium arsenide contains 1-2 at. per cent of silicon.