Since the first silicon transistor was built in 1947, the development of ever tinier and more powerful silicon semiconductor chips has revolutionized our global society, making it possible to communicate and share information in faster and more efficient ways.
Today, advancements using silicon are reaching limits and the material’s drawbacks, like its inability to efficiently transmit light, are becoming issues for semiconductor manufacturers. Already, silicon semiconductors are being used primarily for electronics while compound semiconductors are used in photonic devices such as lasers, solar panels, and LED displays.
By combining electronics and photonics into a single chip, semiconductor manufacturers can open the path to next-generation optoelectronic devices that source, detect and control light to create higher-power electronics. Using optical power for internal operation promises faster, lower-cost chips with applications ranging from energy-efficient data centers to laser-based radar for autonomous vehicles to chemical sensors in medical devices.
Germanium semiconductor materials
As scientists search for ways to expand the capabilities of silicon, a team of researchers at the University of Eindhoven, the Technical University of Munich and other universities recently achieved a significant breakthrough by demonstrating that hexagonal silicon-germanium alloys form an ideal material in which to combine electronic and optoelectronic functions into a single chip. The researchers were able to tune the emission wavelength over a broad range as they added more germanium to the silicon-germanium semiconductor. As part of their work, the researchers used the Thermo Scientific Nicolet iS50R Research FTIR spectrometer to capture luminescence spectroscopy measurements down to the nanosecond.
Using the Thermo Scientific Nicolet iS50R Research FTIR Spectrometer, researchers were able to tune the emission wavelength over a broad range by changing the composition of the silicon-germanium semiconductor (Fadaly, Dijkstra, Suckert, et al., 2020).
Unlike other FTIR spectrometers, which move continuously as they scan across a linear area, the Nicolet IS50R employs a Step-Scan Control System, which repeatedly moves, stops and scans, until the instrument completes multiple scans across an area. Information gathered from a linear scan is analogous to one long exposure image—showing the range of movement captured in milliseconds all in one frame, but without much detail. By comparison, the Step-Scan approach captures high-resolution images taken one after another in ultra-small nanosecond time increments—showing a lot of detail in multiple frames.
Using the Nicolet iS50R as part of their research, this team of researchers took images to measure how the distance between the band gaps affects the frequency at which the electrons move across the chip as more germanium was added. Ultimately, they were able to demonstrate that silicon-alloys with a hexagonal crystal lattice structure can be turned into direct band gap light-emitting materials. The ability to emit light from silicon has eluded the semiconductor industry for decades, and is expected to revolutionize computing by leading to chips that communicate 1,000 times faster than currently possible.
Mike Bradley is a product manager for FTIR and FTIR Microscopy in the Spectroscopy division at Thermo Fisher Scientific.
//
To learn more about how the Nicolet iS50R contributed to this breakthrough research, please see the Nature journal article, Direct-bandgap emission from hexagonal Ge and SiGe alloys.
Leave a Reply