ECE researchers' work on light emitters chosen as APL Editor's Pick


Allie Arp, HMNTL

Packed inside of every cellphone, tablet, laptop, and gaming system is an ever-increasing number and variety of microchips. While silicon chips do much of the heavy lifting, III-V compound semiconductor chips provide vital functions ranging from wireless communication to facial recognition. Compound semiconductor chips are relatively expensive to produce, so a group of HMNTL researchers is working on growing them on low-cost silicon, and they are receiving recognition for their efforts.

Minjoo Lawrence Lee
Minjoo Lawrence Lee

Many III-V devices, such as lasers, are grown as crystalline layers on costly gallium arsenide (GaAs) or indium phosphide (InP) substrates. Growing such devices on silicon would be a lot cheaper, but this process results in imperfections and defects that render them unusable. Illinois ECE Associate Professor Minjoo Lawrence Lee and doctoral student Pankul Dhingra have developed a new way to grow III-V materials that emit red light efficiently on silicon. Their work was chosen as an Editor’s Pick in Applied Physics Letters.

“Getting chosen for an editor’s pick is an honor,” said Lee. “My group and many others worldwide are doing great research on integrating III-V semiconductors with silicon. The field is picking up momentum, infused with new ideas and concepts from other fields of study. I think that’s why the editors liked it.”

In the paper, the duo showed that InP quantum dots grown on silicon wafers emit light similarly to those grown on GaAs wafers despite stark differences in defect density. The quantum dots in the ‘damaged’ crystals emit visible light and show promise for integrated lasers and LEDs used in sensing, displays, and quantum computing.

 “We kind of break the rules of the game,” said Lee. “Defects such as broken atomic bonds are unavoidable in III-V layers grown on silicon. When you inject electrical current into a conventional LED or laser with defects, a lot of that energy can get turned to waste heat. We proved that by using quantum dots, you can have the defects but still emit light efficiently.”

While their research has proven the possibility of efficient red light emission from quantum dots within defective crystals, their next step is to bring the devices to life.

“What we show in this paper is a basic materials study,” said Dhingra. “Our next step is to show high-performance devices on silicon with advantages on scalability and low cost”.

Dhingra’s co-authors on the paper included Dr. Yukun Sun, Dr. Shizhao Fan, Ryan Hool, and Brendan Eng. The full paper can be found here. Lee is affiliated with the HMNTL.


Read the original article on the HMNTL site