Quantum-dot image sensor launch threatens silicon

November 11, 2015 // By Peter Clarke
After nine years of work and having raised more than $100 million in venture capital, InVisage has launched a 13-megapixel sensor that uses a quantum-dot film rather than silicon to capture images.

The company is shooting for the smartphone market to begin with but claims it has the beating of CMOS image sensors in terms of many specifications and therefore in most of if not all applications.

InVisage Technologies Inc. (Menlo Park, Calif.), was founded in 2006 to develop a light-sensitive material to replace silicon. On Nov. 11 in Beijing, the company launched the world's first electronic image sensor that uses quantum-dot material rather than silicon to capture light.

If quantum-dot based light sensing is superior to that of silicon photodiodes – to the degree that InVisage claims – this could represent the beginning of the end for CMOS image sensors which have built up a considerable market on the strength of camera sales into mobile phones. InVisage claims that its Quantum13 sensor will drive "silicon image sensors into obsolescence."
 

At a launch event in Beijing the company demonstrated the 'Quantum13' sensor designed into prototype smartphones. Although InVisage declined to name the smartphone firms involved, Jess Lee, company CEO, told EE Times Europe that the Quantum13 is sampling now and multiple customers are due to receive commercial volume supply in 4Q15.

The quantum-dot material is a II-VI metal-chalcogenide type broadband light absorber, Lee said. And with the quantum confinement produced by using nanoscale particles of the material bound together in an optically transparent carrier material, it becomes a highly efficient photodiode and allows thinner films than the active depth in conventional silicon photodiodes. Only about 0.5-micron depth of QuantumFilm is required compared with 2 or 3 microns depth of silicon photodiode, Lee said.

As a result the Quantum13 embodies a number of advantages over silicon. The 13Mpixel 1.1-micron pixel fits in 8.5mm by 8.5mm module. Light absorption takes place eight times faster than in silicon allowing for the use of a global electronic shutter. Using 0.5-micron thin films – rather than the high aspect ratio wells used for silicon photodiodes – allows much higher incident angles of light, resulting in 4mm camera height module. And thinner camera module allows for thinner smartphone designs.

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