Di Zengfeng

Growth and fabrication of semi-polar InGaN/GaN multi-quantum well light-emitting diodes on microstructured Si (001) substrates

Semi-polar (1 − 101) InGaN/GaN light-emitting diodes were prepared on standard electronic-grade Si (100) substrates. Micro-stripes of GaN and InGaN/GaN quantum wells on semi-polar facets were grown on intersecting {111} planes of microscale V-grooved Si in metal–organic vapor phase epitaxy, covering over 50% of the wafer surface area. In-situ optical reflectivity and curvature measurements demonstrate that the effect of the thermal expansion coefficient mismatch was greatly reduced. A cross-sectional analysis reveals low threading dislocation density on the top of most surfaces. On such prepared (1 − 101) GaN, an InGaN/GaN LED was fabricated. Electroluminescence over 5 mA to 60 mA is found with a much lower blue-shift than that on the c-plane device. Such structures therefore could allow higher efficiency light emitters with a weak quantum confined Stark effect throughout the visible spectrum.

Fabrication of silicon-based flexible opticalwaveguide by edge-cutting transfer technique

Owing to remarkable advantages in flexible, portable, and large area characteristics, inorganic flexible electronics/ photonics have attracted widespread attentions and got full progresses. The key technique for fabrication of inorganic flexible electrical/optical devices is transferring nano-building blocks from conventional rigid substrates to flexible substrates in a manner of controllable, accurate, and ultrahigh alignment. This paper focused on the well-regulated transfer and deterministic assembly of these nano-building blocks onto flexible substrate during transfer printing process, and proposed edge-cutting transfer technique to fabricate and deterministically assemble silicon nanoribbon arrays on flexible substrate. Based on the beam theory and finite element model, the relationships between stress existing in suspended silicon nanoribbons and thickness and width of nanoribbons during edge-cutting transfer process are studied. Moreover, the edge morphologies of the fabricated nanoribbons are investigated with different directions of the initially defined silicon strips. And the silicon nanoribbons with sharp edges can be obtained by optimizing the defined directions of the silicon strips. Ultimately, silicon-based flexible optical waveguide was demonstrated by using the obtained silicon nanoribbon.