Abstract
In this letter, we demonstrate the formation of unique Ga/GaAs/Si nanowire heterostructures, which were successfully implemented in nanoscale light-emitting devices with visible room temperature electroluminescence. Based on our recent approach for the integration of InAs/Si heterostructures into Si nanowires by ion implantation and flash lamp annealing, we developed a routine that has proven to be suitable for the monolithic integration of GaAs nanocrystallite segments into the core of silicon nanowires. The formation of a Ga segment adjacent to longer GaAs nanocrystallites resulted in Schottky-diode-like I/V characteristics with distinct electroluminescence originating from the GaAs nanocrystallite for the nanowire device operated in the reverse breakdown regime. The observed electroluminescence was ascribed to radiative band-to-band recombinations resulting in distinct emission peaks and a low contribution due to intraband transition, which were also observed under forward bias. Simulations of the obtained nanowire heterostructure confirmed the proposed impact ionization process responsible for hot carrier luminescence. This approach may enable a new route for on-chip photonic devices used for light emission or detection purposes.
Highlights
A successful implementation of a new class of materials or means of processing has a potential impact on long-term future technology nodes
In this letter, we demonstrate the formation of unique Ga/GaAs/Si nanowire heterostructures, which were successfully implemented in nanoscale light-emitting devices with visible room temperature electroluminescence
Based on our recent approach for the integration of InAs/Si heterostructures into Si nanowires by ion implantation and flash lamp annealing, we developed a routine that has proven to be suitable for the monolithic integration of GaAs nanocrystallite segments into the core of silicon nanowires
Summary
We achieved the monolithic integration of GaAs and Ga/ GaAs NCs into Si NWs by exploring ion implantation and flash lamp annealing (FLA) routines. For EL in the visible spectral range, distinct emission peaks can be observed with the overall maximum shifting to higher energies for longer GaAs NCs, i.e., increasing breakdown voltages (cf Figure 2b) A high electric field is present in the GaAs depletion layer adjacent to the Schottky interface, accelerating charge carriers, which in turn attain energies in excess of the impact ionization threshold Such hot carriers, instead of transferring energy to phonons, lose energy by elevating valence band electrons to the conduction band and these generated electron−hole pairs themselves generate carrier pairs and the process enters runaway. SEM investigations of nanowire response on ion implantation and annealing, thin crystallite formation, detailed Raman and TEM-EDX investigations, experimental determination of Si nanowire doping type, simulations of Si/GaAs/Si barrier heights, hole concentrations, and impact ionization generation rates (PDF)
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