Fabrication of three-dimensional GaAs-AlGaAS heterostructures for improving carrier injection efficiency in quantum-wire FETs

Three-dimensional (3D) GaAs-AlGaAS heterostructures were grown by selective-area molecular beam epitaxy on a patterned GaAs(0 0 1) substrate to improve the efficiency of carrier transport from the source to the drain through 1D channels in quantum-wire (QWR) field-effect transistors. Prior to the QWR growth, GaAs ridge structures with 2 μm line-and-space patterns, were prepared as the starting materials. The surface of the ridge was chemically treated with an NH₃ solution to improve the surface roughness and thereby to minimize the defect density at the GaAs/AlGaAs interface. Then, GaAs/AlGaAs QWRs were grown on top of the ridge structures with optimum growth conditions. A scanning electron microscope and position-resolved μ-PL measurements along the QWR direction showed that 3D GaAs-AlGaAS heterostructures, where 1D QWRs were adiabatically coupled with a 2D electron gas, were successfully fabricated.