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A simple and robust GaN-on-Si double heterostructure FET (field effect transistor) architecture for GaN-on-Si power switching devices is being demonstrated by IMEC at this year’s IEEE IEDM conference. GaN-compounds are seen as one of the best candidates to replace Si power devices, thanks to their high band gap, generating better transport properties as well as their high electrical breakdown field.

IMEC’s architecture is claimed to meet the normally off-requirements of power switching circuits and is characterized by low leakage and high breakdown voltage, both essential parameters to reduce the power loss of high-power switching applications.

GaN-epilayers grown on large diameter Si wafers, potentially up to 200mm, offer a lower cost technology compared to other substrates.

IMEC obtained a high-breakdown voltage of almost 1000V combined with low on-resistance by growing an SiN/AlGaN/GaN/AlGaN double heterostructure FET structure on an Si substrate. By combining its double heterostructure FET architecture with in-situ SiN grown in the same epitaxial sequence as the III-nitride layers, IMEC succeeded in obtaining e-mode device operation.

The fabrication is based on an optimized process for the selective removal of in-situ SiN. The resulting SiN/AlGaN/GaN/AlGaN double heterostructure FET is characterized by a high breakdown voltage of 980V, an excellent uniformity and a low dynamic specific on-resistance of 3.5 mW.cm² that is well within the present state-of-the-art.

IMEC claims that the new results could lead to a huge market opportunity for GaN-on-Si power devices.