Strain-Induced Pseudoheterostructure Nanowires Confining Carriers at Room Temperature with Nanoscale-Tunable Band Profiles

Abstract

Semiconductor heterostructures play a vital role in photonics and electronics. They are typically realized by growing layers of different materials, complicating fabrication and limiting the number of unique heterojunctions on a wafer. In this Letter, we present single-material nanowires which behave exactly like traditional heterostructures. These pseudoheterostructures have electronic band profiles that are custom-designed at the nanoscale by strain engineering. Since the band profile depends only on the nanowire geometry with this approach, arbitrary band profiles can be individually tailored at the nanoscale using existing nanolithography. We report the first experimental observations of spatially confined, greatly enhanced (>200×), and wavelength-shifted (>500 nm) emission from strain-induced potential wells that facilitate effective carrier collection at room temperature. This work represents a fundamentally new paradigm for creating nanoscale devices with full heterostructure behavior in photonics and electronics.

Elastic strain engineering for unprecedented materials properties

“…This strain-induced exciton funneling effect has been recently verifi ed experimentally, 31 , 32 and the same effect in elastically deformed nanowires was also demonstrated. 33,34 (see article in this issue by Yu et al).…”

Ge-on-Si photonic devices for photonic-electronic integration on a Si platform

“…In a Fabry-Perot resonator of Ge waveguide, a lasing was also reported under an optical pumping [54] and an electrical pumping [55,56], although there is no further report to obtain the lasing. In order to generate a large (> 1%) tensile strain towards direct-gap Ge, an application of micromechanical stress [57] to membrane structures [58,59,60,61] was examined, but no lasing has been obtained yet. Critical process techniques might be required for the laser operation, and further studies are necessary from the viewpoints of material science and device physics.…”

Direct Bandgap Light Emission from Strained Germanium Nanowires Coupled with High-Q Nanophotonic Cavities

“…The result matches our FEM simulations and reveals uniform highly strained Ge along the length of the nanowire. Additionally, because tensile strain reduces the bandgap of Ge, the spatial variation in the strain profile creates a pseudo-hetereostructure which confines carriers to the nanowire region, greatly improving carrier concentrations in the gain medium [26]. used to collect the spectra.…”