Selective MBE growth of GaAs wire and dot structures using atomic hydrogens and their electronic properties

Abstract

The selective growth of GaAs wire and dot structures by molecular beam epitaxy in the presence of atomic hydrogen was studied on a GaAs substrate with stripe and window shaped SiN x mask patterns. It was found that 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 μm. This is ascribed to the longitudinal migration of Ga flowing from the two ends of a stripe to its central zone. The incorporation of Si dopants into a 0.3 μm-wide wire was achieved. Negative magnetoresistance and conductance fluctuations indicative of the one-dimensional nature of electrons were observed. On a 2 x 2 μm square window pattern, a pyramidal structure with two-fold symmetry was formed, on which a GaAs dot with the lateral dimension of 100 nm was grown. Photoluminescence (PL) spectra from this dot exhibited a shoulder structure 15 meV, suggesting the filling of several discrete levels and the slow relaxation of carriers.