Single-photon avalanche diode fabricated in standard 55†nm bipolar-CMOS-DMOS technology with sub-20†V breakdown voltage.

This paper presents a single-photon avalanche diode (SPAD) in 55 nm bipolar-CMOS-DMOS (BCD) technology. In order to realize a SPAD having sub-20 V breakdown voltage for mobile applications while preventing high tunneling noise, a high-voltage N-well available in BCD is utilized to implement the avalanche multiplication region. The resulting SPAD has a breakdown voltage of 18.4 V while achieving an excellent dark count rate of 4.4 cps/µm2 at the excess bias voltage of 7 V in spite of the advanced technology node. At the same time, the device achieves a high peak photon detection probability (PDP) of 70.1% at 450 nm thanks to the high and uniform E-field. Its PDP values at 850 and 940 nm, wavelengths of interest for 3D ranging applications reach 7.2 and 3.1%, respectively, with the use of deep N-well. The timing jitter of the SPAD, full width at half maximum (FWHM), is 91 ps at 850 nm. It is expected that the presented SPAD enables cost-effective time-of-flight and LiDAR sensors with the advanced standard technology for many mobile applications.

Enhanced second-harmonic generation in strained germanium-on-insulator microdisks for integrated quantum photonic technologies.

Quantum photonic circuits have recently attracted much attention owing to the potential to achieve exceptional performance improvements over conventional classical electronic circuits. Second-order χ(2) nonlinear processes play an important role in the realization of several key quantum photonic components. However, owing to their centrosymmetric nature, CMOS-compatible materials including silicon (Si) and germanium (Ge) traditionally do not possess the χ(2) response. Recently, second-harmonic generation (SHG) that requires the χ(2) response was reported in Ge, but no attempts at enhancing the SHG signal have been conducted and proven experimentally. Herein, we demonstrate the effect of strain on SHG from Ge by depositing a silicon nitride (Si3N4) stressor layer on Ge-on-insulator (GOI) microdisks. This approach allows the deformation of the centrosymmetric unit cell structure of Ge, which can further enhance the χ(2) nonlinear susceptibility for SHG emission. The experimental observation of SHG under femtosecond optical pumping indicates a clear trend of enhancement in SHG signals with increasing strain. Such improvements boost conversion efficiencies by 300% when compared to the control counterpart. This technique paves the way toward realizing a CMOS-compatible material with nonlinear characteristics, presenting unforeseen opportunities for its integration in the semiconductor industry.

A sub-wavelength Si LED integrated in a CMOS platform.

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 with sub-wavelength emission area fabricated in an open-foundry microelectronics complementary metal-oxide-semiconductor platform. The light-emitting diode emission spectrum is centered around 1100 nm and the emission area is smaller than 0.14 µm2 (~[Formula: see text] nm). This light-emitting diode has high spatial intensity of >50 mW/cm2 which is comparable with 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 light-emitting diode 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 complementary metal-oxide-semiconductor imager.