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The development of techniques of nanofabrication is presented, using electron beam lithography, applied to semiconductor heterostructures grown by molecular beam epitaxy on non-(100) substrates. The structures studied were fabricated on InGaAs/GaAs single quantum wells, with 15% In concentration and a well width of 4 nm. The arrays of quantum dots were studied by photoluminescence spectroscopy. The optical emission spectra were analyzed with regard to the dot parameters, power density and temperature.Introduction Nanodevices, such as single-electron transistors or quantum wire lasers, require precise lithography with dimensions of the order of 10 nm. Electron beam lithography (EBL) is the method most used to fabricate devices with dimensions of less than 100 nm.Owing to the interest in the dimensionality dependence of a wide variety of physical phenomena, as well as their potential for device applications, low-dimension semiconductor structures have been investigated intensively in the last few years. The effect of lateral quantization in these small structures, whose sizes are comparable to the wavelength of the carriers, results in an increase of the exciton binding energy, density of states and other important physical parameters.The interest in the use of non-(100) surfaces as substrates for epitaxial growth of semiconductor heterostructures such as quantum wells (QWs), superlattices, quantum dots (QDs) [1-6] and devices has significantly increased over the last few years because these structures reveal new and superior properties. The possibility of changing and improving fundamental material properties, growth mechanisms, surface kinetics and impurity incorporation and obtaining new interfaces by growing on crystal orientations other than (100) has led to much research on these physical aspects. The developments in quantum structures have brought out naturally the importance of all surfaces that bound nanodevices. The use of GaAs-based heterostructures grown on non-(100) surfaces has not been conventional due to the natural corrugation of these surfaces. This property can limit the spatial resolution and the quality of the interfaces. To our knowledge no work related to the use of non-conventional GaAs surfaces for nanofabrication using EBL and wet chemical etching has been reported in the literature.

Carbon, being one of the most versatile elements of the periodic table, forms solids and molecules with often unusual properties. Recently, a novel family of three-dimensional graphitic carbon structures, the so-called hyperhoneycomb lattices, has been proposed, with the possibility of being topological insulators [1]. In this work, we present electronic structure calculations for one member (H-0) of this family, using Density Functional Theory and non-equilibrium Green's functions transport calculations to show that the H-0 structure should have strongly anisotropic electronic properties, being an insulator or a conductor depending on the crystalline orientation chosen for transport. Calculations in the framework of Extended Hückel Theory indicate that these properties can only be understood if one considers at least 2 nd nearest-neighbor interactions between carbon atoms, invalidating some of the conclusions of Ref.[1], at least for this particular material.

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