Ge/SiGe-AlN Core-Shell Crystals: E-band Emission for Optical Comms

EE Times Japan Japan

Overview

A joint research group from Japan and South Korea has developed Ge/SiGe-AlN core-shell crystals that emit light in the E-band (1360–1460 nm). The team proposed a “shell-first” growth model driven by Plateau-Rayleigh instability to explain the formation of these structures.

In Depth

Key Findings

A joint research team comprising Nagoya University, the Electronics and Telecommunications Research Institute (ETRI), Kookmin University, and Korea National Ocean University has confirmed that Ge/SiGe-AlN core-shell crystals emit light within the E-band (1360–1460 nm), a critical spectrum for optical fiber communications. Room-temperature photoluminescence measurements identified specific emission peaks at 1372 nm, 1377 nm, 1381 nm, and 1392 nm.

Technical Details

The researchers combined Ge (germanium)/SiGe (silicon germanium) semiconductors with AlN (aluminum nitride) to create core-shell crystals, where a central core is surrounded by a different material shell. To analyze the resulting structures, the group utilized X-ray CT and electron microscopy. These observations revealed various morphologies, including structures with internal cavities and those where Ge/SiGe materials were partially incorporated into the interior.

Based on these results, the team proposed a “shell-first” growth model. Unlike conventional processes where the core forms first, this model suggests that the AlN-containing shell structure forms first, subsequently incorporating the Ge/SiGe materials. The researchers attribute this unique growth mechanism to the influence of Plateau-Rayleigh instability.

Background and Context

Core-shell crystals are utilized to combine semiconductors with different properties to enable new optical and electronic devices. However, the specific processes of core and shell formation, as well as their resulting optical characteristics, had not been sufficiently elucidated until this study.

Significance and Outlook

The ability to achieve E-band emission using Ge/SiGe-AlN materials provides a potential new material path for optical communication components. The research was conducted by a diverse team including Choi Sunghoon (ETRI), Park Jun-Seok and Won Joon Bong (Kookmin University), Lee Jae Hak and Kim Kyoung Hwa (LNBS), Ahn Hyung-Soo, Kwon Eunmin, Kim Sohee, Kim Myungjun, and Jeong Donghyeon (Korea National Ocean University), as well as Anna Honda, Yoshio Honda, and Tsuyoshi Kato from Nagoya University’s Institute for Materials and Systems.

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