A sub-wavelength Si LED integrated in a CMOS platform

Abstract A nanoscale on-chip light source with high intensity is desired for various applications in integrated photonics systems. However, it is challenging to realize such an emitter using materials and fabrication processes compatible with the standard integrated circuit technology. In this letter, we report an electrically driven Si light-emitting diode (LED) with sub-wavelength emission area fabricated in an open-foundry microelectronics CMOS platform. The LED emission spectrum is centered around 1100 nm and the emission area is smaller than 0.14 μm( ≈ 400 nm diameter). This LED has high spatial intensity of > 50 mW/cm which is comparable with the state-of-the-art Si-based emitters with much larger emission areas. Due to sub-wavelength confinement, the emission exhibits a high degree of spatial coherence, which is demonstrated by incorporating the LED into a compact lensless in-line holographic microscope. This centimeter-scale, all-silicon microscope utilizes a single emitter to simultaneously illuminate ≈ 9.5 million pixels of a CMOS imager.