The Engineer

Image sensors based on quantum dots

News

InVisage Technologies, based in Menlo Park, California, has developed what it claims are the world’s first commercial quantum-dot-based image sensors.

The company’s so-called QuantumFilm technology was developed by InVisage after years of research under the guidance of the company’s chief technical officer, Ted Sargent.

The technology is based on quantum dots – semiconductors with unique light-capture properties. QuantumFilm works by capturing an imprint of a light image on the quantum dots and then employs the silicon beneath it to read out the image and turn it into digital signals.

InVisage spent three years engineering the quantum-dot material to produce image sensors that could be integrated with standard CMOS manufacturing processes.

Just nanometres in size, the quantum-dot-based material is deposited directly on top of the wafer during manufacturing. The material is added as a final wafer-level process, which allows for easy integration into standard semiconductor foundries. The process – akin to coating a layer of photoresist onto a standard wafer – adds minimal cost on top of the standard layers of silicon processes.

Silicon-based image sensors – the technology used today for all digital cameras, including handheld, professional, mobile-phone, security and automotive cameras – capture, on average, 25 per cent of light. QuantumFilm, on the other hand, is claimed to capture 90-95 per cent, enabling better pictures even in the most challenging lighting conditions.

The first target market for QuantumFilm is mobile handsets, where there is the greatest demand for small, high-performance image sensors.

InVisage was founded in 2006 and is led by veterans from the image sensor and advanced semiconductor materials industry. It employs 30 people at its Menlo Park headquarters and has received more than $30m (£20m) in funding from RockPort Capital, Charles River Ventures, InterWest Partners and OnPoint Technologies. Its technology is protected by 21 patents and patents pending.

The first QuantumFilm image sensors, targeting high-end mobile handsets and smartphones, will sample in the fourth quarter of 2010.

InVisage will be giving a talk about its technology at Image Sensors Europe 2010 on 24 March in London.