Incorporation of Sn on GaAs (111)A substrates by molecular beam epitaty
Behavior of Sn as donor species in the MBE growth of GaAs on (111)A substrates has been investigated by varying the growth temperature from 460 to 620°C, As4:Ga flux ratio from 4 to 25, and Sn concentration from 1016 to 1020 atoms cm-3. Secondary ion mass microscopy measurements show that Sn does not surface segregate on (111)A substrates under this growth condition, in contrast to that on (001) substrates. Sn is uniformly incorporated throughout the bulk of the grown layer for all samples, apart from the most highly doped ones. To increase the Sn carrier concentration on the (111)A substrates, the measured carrier concentration shows that doping should be carried out at a low growth temperature and/or high As4:Ga flux ratio.