SELECTIVE MBE GROWTH OF GAAS WIRE AND DOT STRUCTURES USING ATOMIC HYDROGENS AND THEIR ELECTRONIC-PROPERTIES

The selective growth of GaAs wire and dot structures by molecular beam epitaxy in the presence of atomic hydrogen was studied on a GaAs subs trate with stripe and window shaped SiNx mask patterns. It was found t hat 20 nm ridges were successfully formed on long stripe patterns but the ridge width increased substantially when grown on short stripes of less than several mu m. This is ascribed to the longitudinal migratio n of Ga flowing from the two ends of a stripe to its central zone. The incorporation of Si dopants into a 0.3 mu m-wide wire was achieved. N egative magnetoresistance and conductance fluctuations indicative of t he one-dimensional nature of electrons were observed. On a 2 x 2 mu m square window pattern, a pyramidal structure with two-fold symmetry wa s formed, on which a GaAs dot with the lateral dimension of 100 nm was grown. Photoluminescence (PL) spectra from this dot exhibited a shoul der structure 15 meV, suggesting the filling of several discrete level s and the slow relaxation of carriers.