Direct Electrochemical Synthesis of Epitaxial Germanium Nano- and Micro-Wire Arrays at Room Temperature in Water

The ability to synthesize structurally and electrically integrated group IV semiconductor nanostructures directly into devices is desirable for continued miniaturization of transistors. However, the most common nanofabrication architectures are largely incompatible with the high temperature semiconductor growth processes currently available. We developed a new aqueous electrochemical synthesis strategy termed electrochemical liquid-liquid-solid (ec-LLS) growth that uses a liquid metal as a traditional cathode and as a recrystallization solvent to synthesize crystalline semiconductors at room temperature. This presentation will highlight data that extends the ec-LLS strategy to using nanoscale arrays of liquid gallium (Ga(l)) and Ga_xIn_1-x alloy electrodes supported on Si wafers for the electrodeposition of epitaxial Ge nanostructures. Detailed electron microscopy will be presented which verifies the epitaxial and single crystalline nature of the structures integrated with the wafer substrates. The influence of electrode composition on resultant morphology, crystal quality, and solid-state electrical properties will be discussed. The coupling of this ec-LLS synthesis technique with liquid metal photolithography techniques developed in our lab will also be mentioned within the context of growing complex 1D, 2D and 3D Ge crystals with high degrees of spatial control.