Electronics and Optics on One Chip Getting Light out of Silicon
November 13, 2017 | University of TwenteEstimated reading time: 2 minutes
Electronics and light don't go well together on a standard 'CMOS' chip. Researcher Satadal Dutta of the University of Twente succeeded in introducing a light connection into the heart of a semiconductor chip. In this way, two circuits can communicate. Or: the worlds of electronics and photonics are connected.
What is particularly attractive about Dutta's solution is that no special materials or manufacturing processes are needed: the light comes from silicon. The light source, detector and the light channel can be made using the technology that is used to make the electronic circuits. Fully optical circuits are available nowadays, but they use materials like indium phosphide and gallium arsenide, which can't easily be combined with the CMOS chip processes used for semiconductor chips you'll find in today's smartphones, for example.
Avalanche LED
The alternative would be: make a LED out of silicon. And that's the problem: silicon only emits a tiny amount of infrared light, while a detector made out of silicon needs visible light. They are talking and listening at different wavelengths. Dutta therefore chooses a remarkable way out: connect the LED reverse. At low voltages, there's no current, but at a voltage that is high enough, there will be a small current that amplifies itself like an avalanche. In this 'avalanche mode', the LED will transmit visible light. Using the same process, the light detector, as well as the light channel in-between can be made. Thanks to the special comb structure that Dutta designed, the light source gets more uniform and energy efficient.
Isolation
An optical link on a chip is a good way to 'galvanically' isolate two circuits from each other. This is often necessary in cases where one circuit is a low-voltage and low-current one, while the other is a high-power circuit. They should be connected, but not by conducting wires, for reasons of safety. A classic transformer is an option then, but an optical connection is often used as well. Until now, this is a separate 'optocoupler', which is large and has a limited bit rate. Dutta's new solution is much more compact as an alternative: it total, it is just a few tens of microns and it offers the protection that's needed. Compared to optical channels in full-optical circuits, the energy consumption is relatively high, as there is quite some scattering of light. On the other hand: designing the electronics around the optical link in an efficient way, the amount of light needed for a successful connection, can be kept to a minimum.
Connecting worlds
All-optical circuits may become the 'new electronics', predictions say. In the transition from electronic to optic circuits, hybrid circuits, like the one Dutta designed, could play an important role.
Satadal Dutta (1990, Barrackpore, India) did his PhD research in the Semiconductor Components group of Prof Jurriaan Schmitz, together with the Integrated Circuit Design group of Prof. Bram Nauta. Dutta defended his thesis 'Avalanche-mode silicon LEDs for monolithic optical coupling in CMOS technology' on 8 November. It was supported financially by NWO-TTW in The Netherlands and by NXP Semiconductors.
Suggested Items
iNEMI Names Grace O'Malley CTO
05/02/2024 | iNEMIThe Board of Directors of the International Electronics Manufacturing Initiative (iNEMI) has named Grace O'Malley Chief Technical Officer (CTO).
ZESTRON Academy Launches 2024 Advanced Packaging & Power Electronics Webinar Series
05/01/2024 | ZESTRONZESTRON, the leading global provider of high-precision cleaning products, services, and training solutions in the electronics manufacturing and semiconductor industries, proudly announces the launch of its highly anticipated webinar series on Advanced Packaging & Power Electronics, a webinar series on the latest innovations, cleaning, and corrosion challenges.
NextFlex Convenes the Hybrid Electronics Community at Binghamton University
05/01/2024 | NextFlexBinghamton University hosted the NextFlex hybrid electronics community on April 18 for a day of expert presentations, breakout sessions on technology and manufacturing topics, and networking.
HQ NextPCB of HQ Electronics Debut on the International Stage for Electronics Manufacture at IPC APEX 2024
05/01/2024 | PRNewswireHQ NextPCB of HQ Electronics, a leading Chinese-based multilayer PCB manufacturer and assembly house showcased its industrial prowess on the international stage for the first time at the IPC APEX Expo 2024.
GPV’s Q1 2024 Interim Financial Report Shows Strong Navigation in Uncertain Times
05/01/2024 | GPVDanish-based GPV recorded an expected drop in sales to DKK 2.3 billion for the first quarter of 2024. The decline also affected the operating profit, which was DKK 155 million compared to DKK 179 million in the same quarter last year, although the EBITDA margin was maintained. In general, demand has been softer in 2024, but GPV continues to invest for the long-term and expects the trend to turn in the second half of 2024.