Patterned growth on high-index GaAs (n11) substrates: Application to sidewall quantum wires

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Abstract
We have recently found a new phenomenon in the selectivity of growth by molecular‐beam epitaxy on patterned GaAs (311)A substrates to form a fast growing sidewall on one side of mesa stripes oriented along the [01−1] direction. Preferential migration of Ga atoms from the mesa top and bottom toward the sidewall forms a smooth convex curved surface profile without facets. Comparison of patterned growth on other high‐index (n11)A&B surfaces shows this growth mode to be unique for GaAs (311)A substrates. Lateral quantum wires are realized for step heights in the quantum‐size regime. Quantum confinement of excitons in the wires is demonstrated by the transition from two‐dimensional to magnetic confinement with increasing magnetic field. For device applications it is important that the wires can be vertically stacked in the growth direction without increase in interface roughness and wire size fluctuations.