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Monday Oct 03, 2022

Chip Photodetection – 2D Material Heterojunctions in “Post-Moore Era” Microelectronics

Photonic integrated circuits, or PICs, use photons to carry information and have high transmission speeds, low delays, and anti-electromagnetic crossingtalk. These benefits are expected to address the problems with microelectronics chips’ speed, power consumption and integration density. This is crucial for promoting breakthroughs and quantum information technology in microelectronics, micro-sensing, and microelectronics in the “postMoore era.”

Photonic integrated chips are making great strides today, thanks to the use of information technology. Silicon PIC can be used with mature CMOS technology to produce low-cost, large-scale production. Silicon nitride PIC can tolerate moderately high optical power, large fabrication errors, and Lithium niobate PIC can achieve perfect electro-optic modulations using low driven voltages and high linearity. However, the monolithic integration waveguides/photodetectors with a single component is one of their major weaknesses. The PIC materials can’t absorb light, so it is impossible to create integrated photodetectors from a single material. This problem was solved by hetero-integrations (e.g., Ge, III-V compound semiconductors etc.) of bulk absorptive materials. On-chip PICs have been successfully implemented. It still faces challenges, such as high costs and complicated fabrication processes.

Two-dimensional (2D), materials have been popularized as photon-absorption materials for chip-integrated photodetectors. Two-dimensional (2D) materials do not have any surface dangling bond, so there are no lattice-mismatch restrictions to hetero-integrate them using PICs. There are many electronic and optical properties available in the 2D material family, including black phosphorus, semi-metallic graphene and insulating boron. The appropriate 2D materials can be used to build chip-integrated photodetectors that operate at different spectral ranges.


A new paper, published in the journal Light Science & Application, was published by a research team led by Professor Xuetao Gan, Key Laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information Technology. The paper, which was published on April 20, 2022, reports that van der Waals PN heterojunctions of two-dimensional materials on optical waveguides could be a promising strategy for chip-integrated photodetectors. It can produce low dark current, high speed, and high responsivity and light.

The researchers used natural p-doped BP, and n-doped MoTe for heterostacking. They were able to successfully fabricate a van der Waals PN heterojunction.

Second, 2D materials don’t need to be concerned about lattice mismatch because there are no dangling bond surfaces on 2D materials as compared to traditional semiconductors.

The preparation of source-drain electrodes can be integrated onto the photonic platform using the “stacking timber” technology. They can be placed on both sides without the need for cumbersome processes like photolithography.

This greatly simplifies the manufacturing process, and prevents contamination of the interface during processes like photolithography. This greatly enhances the performance of your device.

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