InAs/InGaAs self-assembled quantum dots grown on (311)B GaAs by molecular beam epitaxy

We have fabricated InAs/InGaAs self-assembled quantum dots on (311)B GaAs substrates. By RHEED observation, the critical thickness for SAD formation on (311)B is measured to be almost the same as that on (100). Uniform SAD structures on (311)B are confirmed by AFM observation. PL measurements on InAs SADs show a reduced linewidth from (311)B SADs compared with (100) SADs. In the measurements, an intense PL peak from the wetting layer that exists under the SAD layer was observed from the (311)B sample. We introduced compound SAD structures which are intended to suppress the luminescence from the wetting layer. At room temperature as well as at 2 K, narrow PL emissions are observed from the compound SADs of InGaAs dots on an InAs wetting layer. The linewidths are about one half of those from the (100) SADs. The narrowest PL linewidth of 41 meV was obtained at room temperature. One reason for this improvement is expected to be the improved uniformity in (311)B SADs, which may be achieved by the high surface adatom mobility. This improvement demonstrates the advantage of using (311)B substrates in SAD growth by MBE.