Project researches innovative 3D sensor from Siegen

What unlocks smartphones today, can protect lives in cars and will provide even more realistic camera images tomorrow is often only a few millimetres in size: modern 3D image sensors. Researchers at the University of Siegen have developed a completely new type of 3D sensor for integrated cameras - the "intrinsic photomixing detector". While an international patent procedure is currently underway for the prototype, a new research project led by Dr.-Ing. habil. Andreas Bablich is investigating the practical application possibilities, the manufacturing process and the performance of the sensor. The project, called PICASSO, is being funded by the German Research Foundation (DFG) with around 430,000 euros. The aim is to create the basis for particularly compact and cost-effective 3D sensors.

"Initial tests suggest that our new light sensors are not only smaller and require fewer electronics than conventional systems - but that they can also measure more precisely and sensitively," says Bablich from the Chair of Graphene-based Nanotechnology at the University of Siegen.

Like many modern 3D sensors, the new sensor also works according to the principle of so-called time-of-flight measurement: In this process, light is emitted, reflected by an object and then detected again. The distance to the object can be calculated from the time it takes for the light to travel this distance. For a particularly accurate measurement, the received light signal is compared with an internal electrical reference signal.

The key difference between the new sensor and the existing technology is that while conventional sensors require additional, complex electronics for this comparison, the new 3D sensor compares the signal directly in the component. This is made possible by a special property of the semiconductor material used. "Our sensors do not consist of perfectly ordered crystals, but of a material with targeted crystal defects," explains Bablich. "These irregularities in the atomic structure ensure that different signals can be mixed and compared directly in the sensor."

Over the next three years, the PICASSO project will investigate how exactly the new sensors can be optimally constructed and manufactured. "A sensor consists of various nanometer-thin layers that are systematically joined together and each have different properties," explains Bablich. He and his team want to take a closer look at how the individual layers have to be structured, how they are composed at an atomic level and how thick they should be, for example, in order to achieve optimum electro-optical properties for the sensor. In addition to the development of such sensor concepts, the performance of the sensors is also to be precisely evaluated with the help of an in-house measurement setup.

Bablich, who recently moved into his office in the new INCYTE research center on the Adolf Reichwein Campus of the University of Siegen, is delighted to be able to use the innovative research infrastructure of the laboratories there: "Here at INCYTE, we will have completely new and unprecedented opportunities to produce sensors and sensor materials in the future," says Bablich. "Being able to use this state-of-the-art infrastructure as part of our project is fantastic. I'm really looking forward to it."

With the PICASSO project ("Photoinduced current amplification and intrinsic frequency mixing for rangefinders, 3D image sensors and next-generation systems"), the researchers want to take an important step towards a new generation of high-performance, compact 3D sensors - with great potential for applications ranging from consumer electronics to security technology.