Si/(Si)Ge heterostructures grown via low-temperature molecular beam epitaxy as building blocks for novel device concepts
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
2022 E-MRS Fall Meeting
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
Current research advances for classical [1] and quantum [2] Si(Ge)-based light emitters raise expectations to finally overcome the restrictions imposed by the indirect bandgap nature of group-IV semiconductors. However, emitter integration in efficient electrically-pumped devices is limited by the absence of lattice-matched compounds that allow confining injected carriers to the emitter-site via type-I double-heterostructures (DHS), as it is state-of-the-art for the III-V (Al)GaAs system.
Common knowledge suggests that the type-II band alignment and the limited critical thickness of strained, pseudomorphic, and Ge-rich Si1 xGex on Si(001) layers impede DHS-formation.
We present an extensive study of Si1-xGex epilayers with variable Ge contents of 0.35< x< 1 and layer thicknesses of 1.6< Ɵ< 16.6 nm grown via ultra-low-temperature molecular beam epitaxy [3]. We initially focused on the surface roughness and -morphology and any signs of elastic and plastic relaxation. Despite growth temperatures < 350°C, the layers exhibit excellent structural quality, highlighted via X-ray diffraction, luminescence spectroscopy, and transmission electron microscopy experiments. These findings allowed for the realization of first-generation group-IV double-heterostructure LEDs, operating above room temperature.