We have demonstrated an up to seven-fold enhancement of photoluminescence from silicon-rich silicon nitride film due to a single photonic crystal cavity. The enhancement is partially attributed to the Purcell effect. Purcell factor predicted by FDTD calculations is 32 for a linear three-defect cavity mode with computed quality factor of 332 and mode volume of 0.785 (λ/n) 3 . Experimentally measured cavity quality (Q) factors vary in the range of 200 to 300, showing excellent agreement with calculations. The emission peak can be tuned to any wavelength in the 600 to 800 nm range.Silicon-based light sources compatible with the mainstream CMOS technology are highly desirable because they will have a low manufacturing cost relative to III/V semiconductor diodes, and it will be easier to integrate them with electronic components on the same chip. Photoluminescence (PL) from silicon-rich silicon nitride and, more commonly, oxide films with 3 to 5 nm precipitates of silicon nano-crystals (Si-nc) in the dielectric matrix, has been studied.1,2 The luminescence is attributed to confined exciton recombination in the Si-nc or to the radiative recombination centers located at the interface between the Si-nc and the dielectric.2 Internal quantum efficiencies can be as high as 59%, 3 and optical gain for Si-ncs has been demonstrated. 2 Confining luminescent material in an optical micro-cavity enhances the emission by restricting the resonant wavelength to a directed radiation pattern that can be collected effectively, and by reducing radiative lifetime of the on-resonance emitters due to the Purcell effect. 4,5 Reduction in radiative lifetime is particularly important for the development of lasers based on Si-ncs because it makes radiative recombination compete more favorably with non-radiative recombination processes which increase at higher pump powers. In this paper, we demonstrate light emitters based on two-dimensional (2-D) photonic crystal (PC) cavities fabricated in silicon-rich silicon nitride membrane. We used 2-D PC nanocavities because of their high Q-factor (Q) values and small mode volumes (V), since both are necessary for the Purcell effect. Planar geometry of the implementation is well suited for integration with other optical devices on a chip.The structures were fabricated starting from bare silicon wafers. At the first step, a 500-nm-thick oxide layer was formed by wet oxidation. At the second step, a 250-nmthick layer of silicon-rich silicon nitride was deposited by a chemical vapor deposition from NH 3 and SiH 2 Cl 2 gases at 850°C. Next, a positive electron beam resist, ZEP, was spun on a wafer piece to form a 380-nm-thick mask layer. Photonic crystal pattern was exposed on the Raith 150 electron beam system. After development, the pattern formed in the resist layer was transferred into the silicon nitride layer by reactive ion etching with NF 3 plasma 6 using ZEP pattern as a mask. All remaining resist was removed by oxygen
We have demonstrated an up to seven-fold enhancement of photoluminescence from silicon-rich silicon nitride film due to a single photonic crystal cavity. The enhancement is partially attributed to the Purcell effect. Purcell factor predicted by FDTD calculations is 32 for a linear three-defect cavity mode with computed quality factor of 332 and mode volume of 0.785 (λ/n) 3 . Experimentally measured cavity quality (Q) factors vary in the range of 200 to 300, showing excellent agreement with calculations. The emission peak can be tuned to any wavelength in the 600 to 800 nm range.Silicon-based light sources compatible with the mainstream CMOS technology are highly desirable because they will have a low manufacturing cost relative to III/V semiconductor diodes, and it will be easier to integrate them with electronic components on the same chip. Photoluminescence (PL) from silicon-rich silicon nitride and, more commonly, oxide films with 3 to 5 nm precipitates of silicon nano-crystals (Si-nc) in the dielectric matrix, has been studied. 1,2 The luminescence is attributed to confined exciton recombination in the Si-nc or to the radiative recombination centers located at the interface between the Si-nc and the dielectric. 2 Internal quantum efficiencies can be as high as 59%, 3 and optical gain for Si-ncs has been demonstrated. 2 Confining luminescent material in an optical micro-cavity enhances the emission by restricting the resonant wavelength to a directed radiation pattern that can be collected effectively, and by reducing radiative lifetime of the on-resonance emitters due to the Purcell effect. 4,5 Reduction in radiative lifetime is particularly important for the development of lasers based on Si-ncs because it makes radiative recombination compete more favorably with non-radiative recombination processes which increase at higher pump powers. In this paper, we demonstrate light emitters based on two-dimensional (2-D) photonic crystal (PC) cavities fabricated in silicon-rich silicon nitride membrane. We used 2-D PC nanocavities because of their high Q-factor (Q) values and small mode volumes (V), since both are necessary for the Purcell effect. Planar geometry of the implementation is well suited for integration with other optical devices on a chip.The structures were fabricated starting from bare silicon wafers. At the first step, a 500-nm-thick oxide layer was formed by wet oxidation. At the second step, a 250-nmthick layer of silicon-rich silicon nitride was deposited by a chemical vapor deposition from NH 3 and SiH 2 Cl 2 gases at 850°C. Next, a positive electron beam resist, ZEP, was spun on a wafer piece to form a 380-nm-thick mask layer. Photonic crystal pattern was exposed on the Raith 150 electron beam system. After development, the pattern formed in the resist layer was transferred into the silicon nitride layer by reactive ion etching with NF 3 plasma 6 using ZEP pattern as a mask. All remaining resist was removed by oxygen
To develop a new device layer transfer technology with porous layer splitting, CMOS FETs were successfully fabricated on epitaxial layers with different thicknesses over porous silicon for the first time. FETs on more than 300nm thick epitaxial films show satisfactory electrical performance. A fabricated active layer was successfully transferred on a flexible plastic substrate for the first time. Transferred devices also show excellent performance. This technology is applicable to flexible single crystal ICs and to thermal cooling of active layers.
We present the design, fabrication and preliminary experiments of two-dimensional photonic crystal cavities made in nanoporous silicon luminescent at 700-800 nm. Enhancement in photoluminescence extraction efficiency at the resonant wavelength is expected due to Purcell effect and directed radiation pattern defined by the cavity. Such cavities should also enhance nonlinearities exhibited by porous Si beyond what is observed in one-dimensional distributed Bragg reflection cavities due to their small mode volumes and modest quality factors. This design aligns itself well to integration with conventional silicon based electronics on a single chip.
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