Passivation of interfacial states for GaAs- and InGaAs/inp-based regrown nanostructures

The interfacial charge density of regrown structures was studied for several different material systems: GaAs, InGaAs/InP, and InAlAs-InGaAs superlattice structures on InP. The particular application of interest is in the fabrication of nanoscale devices. Such structures require a very low density of interfacial charge at their exposed surfaces in order to avoid Fermi-level pinning and subsequent lateral carrier depletion across the structure. (110)-Oriented samples, mimicking the exposed sidewalls of nano-etched structures, were plasma-etched using a variety of gas-phase chemistries. The interfacial charge density at regrown interfaces was studied using capacitance-voltage (CV) and electrochemical CV techniques after in situ and ex situ pretreatments and epitaxial regrowth. The minimum interfacial charge densities obtained for these material systems were <10 ¹¹ cm ^-2. Preferential regrowth around etched nanopillars was demonstrated for InP-based structures.