UA-35051261-1

The Quantum Semiconductor technology platform is centered on the monolithic integration of epitaxial SiGeC films, in particular, superlattices with sophisticated SiGeC compositions and doping profiles, with conventional CMOS technology. The band-gap engineering allowed by SiGeC superlattices enables radically improved optoelectronic properties compared to pure Silicon or Germanium, including much higher efficiency light absorption and light emission, across a wide range of wavelengths, including wavelengths longer than those covered by Ge or InGaAs.

The improved optoelectronic properties can benefit many types of devices such as:
1) Advanced Vertical MOSFETs, suitable for the 10nm node and smaller;
2) CMOS Image Sensors (CIS) for multispectral imaging, from UV through IR;
3) Optical/photonic receivers and interconnects for computing and communications;
4) High efficiency Silicon-based Solar-Cells, integrated with CMOS;
5) CMOS-integrated Thermoelectric Coolers.

Quantum Semiconductor’s imaging platform is applicable to all markets that use imaging, including Ultra-violet, Visible, and Infra-red. Our approach is fundamentally different than the typical sensor manufactured today, because the photo-diode uses an epitaxial thin film for the absorption of the incoming photons, instead of the potential well formed by ion-implantation that is used conventionally. We have decoupled the photon collection process from CMOS junction engineering, thereby allowing our devices to track Moore’s Law with each new design generation, as well as use the most advanced substrates for state-of-the-art CMOS such as fully depleted thin-film SOI. Because our photodiodes are not coupled to the potential well, they can be operated in modes which are not possible for conventional CMOS photodiodes including as an avalanche photodiode (APD). In conventional photodiodes, one incoming photon results in one electron hole-pair, but in APDs, one incoming photon results in a multitude of electron-holes being formed, thereby providing an inherent magnification of the signal. This sensitivity results in sensors with extreme low light sensitivity; coupled with our patented ADC and column-[parallel circuitry results an extremely large dynamic range.

The epitaxial SiGeC film, which forms the absorption layer of the photo-diode, determines the wavelength of operation and the Quantum Efficiency (QE) over the entire wavelength range. A significantly higher QE across all wavelengths, enables the Quantum Semi technology to take advantage of the full solar spectrum. Our SiGeC+CMOS technology solves three critical problems facing camera and camera systems makers: (1) High resolution imaging in low light; (2) Imaging scenes with dynamically changing bright and dark areas (wide dynamic range); and (3) High resolution imaging in daylight and at night with one sensor. Current technologies for visible and infra-red imaging have reached technological roadblocks which have stalled further improvement and no single technology exists today which can be used for multi-spectral imaging.

Avalanche photodiodes emit light when operated above the breakdown voltage of the diode. The wavelength of the emitted light is in the same range as the light absorbed. An individual photodiode can operate as either a light absorber or a light emitter depending on the applied voltage and can switch back and forth countless times.

Epitaxial SiGeC films are widely used in the manufacture of BiCMOS devices and are compatible with existing silicon manufacturing equipment and technology. These conventional films are random alloys with various doping profiles, with a small concentration of C and typically less than 25% Ge. The Quantum Semiconductor SiGeC superlattice films are highly ordered monolayer arrays which can be manufactured on the same production equipment as SiGeC random alloys. The infra-red shift in light absorption and light emission depends on the film composition.

Beyond image sensors, the Quantum Semiconductor platform can be used for other applications which benefit from having an extended wavelength absorption or emission range. For example, high efficiency photovoltaic cells can take advantage of the full solar spectrum and be easily integrated with other CMOS functionality.

Silicon photonics will also benefit from the unprecedented operation of this silicon based technology to both absorb and emit light at the 1.55µm range. Today, products are made from a myriad of different materials, many of which are incompatible with each other and expensive. For some materials, wafers sizes are too small to benefit from economies of scale, even if standard processing capabilities existed. To couple these specialty devices with silicon devices in useful circuits, requires two separate chips, expensive packaging, and a much longer development cycle. Our technology solves this problem of incompatibility by enabling the use of silicon for light emission and absorption, in tandem with additional on-chip electronics fabricated on the same silicon chip. Since our technology is based on silicon we take advantage of the huge world-wide investment in silicon and in CMOS technology by being able to use standard chip fabrication equipment and state-of-the-art silicon wafer sizes.