The authors report compact and chemically homogeneous In-rich InGaN layers directly grown on Si (111) by plasma-assisted molecular beam epitaxy. High structural and optical quality is evidenced by transmission electron microscopy, near-field scanning optical microscopy, and X-ray diffraction. Photoluminescence emission in the near-infrared is observed up to room temperature covering the important 1.3 and 1.55 μm telecom wavelength bands. The n-InGaN/p-Si interface is ohmic due to the absence of any insulating buffer layers. This qualitatively extends the application fields of III-nitrides and allows their integration with established Si technology.
The authors discuss and demonstrate the growth of InN surface quantum dots on a high-In-content In0.73Ga0.27N layer, directly on a Si(111) substrate by plasma-assisted molecular beam epitaxy. Atomic force microscopy and transmission electron microscopy reveal uniformly distributed quantum dots with diameters of 10–40 nm, heights of 2–4 nm, and a relatively low density of ∼7 × 109 cm−2. A thin InN wetting layer below the quantum dots proves the Stranski-Krastanov growth mode. Near-field scanning optical microscopy shows distinct and spatially well localized near-infrared emission from single surface quantum dots. This holds promise for future telecommunication and sensing devices.
Uniform, compact, and thick InGaN layers are grown on Si(111) substrates by plasma-assisted molecular beam epitaxy without any buffer layers at low temperatures of around 320 C. By adjusting the Ga/In flux ratio, InGaN layers with In compositions between 10 and 33% are obtained, providing emission covering the whole visible spectral range. The In composition varies less than 2% over large areas, and the singlecrystalline hexagonal InGaN layers have a well-defined epitaxial relationship with the Si substrate. Photoluminescence is observed up to room temperature, opening the prospect for the direct integration of InGaN light-emitting devices with Si technology.
Both crystal structure and energy band-structure changes caused by As+ implantation and by subsequent annealing in GaAs and in an In0.253Ga0.747As quantum well are studied. We demonstrate that the main implantation impact to the crystal structure is the creation of a large number of point defects and strong compressive strain of up to −0.1%. Raman and x-ray data demonstrate almost complete structural recovery for rapid thermal annealing temperatures⩾600 °C. While the lattice expansion becomes relaxed by annealing, the implantation-induced ionized point defects are still present up to the highest annealing temperatures applied. Under these circumstances, a 22 meV blueshift of the heavy-hole–electron (1hh–1e) transition within the quantum well and a substantial reduction of the nonequilibrium carrier lifetime remain as consequence of implantation.
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