Fabrication and characterization of 0.2 to 6 μm GaInAs/InP electron waveguides

We demonstrate fabrication technology and characterization results of GaInAs/InP electron waveguides with lengths between 0.2 and 6 μm. The waveguides, 50 to 100 nm wide, are produced by deep wet etching of high mobility 2DEG MOVPE-grown G_0.25In_0.75As/InP structures. The waveguide structures are defined by electron beam lithography and a nonselective etching in either HCl:CH₃COOH:H₂O₂ or HBr-based solutions. A 250 nm-thick ZEP520 electron beam resist is used as an etch mask after a post-development baking at 120°C to enhance its adhesion to the substrate. After etching, the structures were regrown by nominally undoped InP layer in a low-pressure MOVPE process or by Fe-doped InP in an atmospheric pressure hydride vapor phase epitaxy (HVPE). The Fermi energy is controlled by applying voltage to resist-insulated top gate or side gates. A well defined quantized conductance at 0.3 K of heterostructurally-defined electron waveguides with length of up to 3 μm is demonstrated