Heavily doped n++ GaN cap layer AlN/GaN metal oxide semiconductor high electron mobility transistor

Karami, K. , Taking, S., Dhongde, A., Ofiare, A., Al-Khalidi, A. and Wasige, E. (2021) Heavily doped n++ GaN cap layer AlN/GaN metal oxide semiconductor high electron mobility transistor. International Journal of Nanoelectronics and Materials, 14, pp. 45-51.

Abstract

In this work, we report on the processing and device characteristics of n++ GaN/AlN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMTs). The AlN/GaN structure is capped with a highly doped n++ GaN layer which provides more free electrons in the cap layer thus helps in reducing the Ohmic contact resistance. However, this layer in the gate region needs to be removed prior to gate metal deposition to avoid a conducting path between gate metal and the cap layer. A conducting path between the gate metal and GaN cap layer creates gate to source and gate to drain short circuit. A selective etching recipe was developed between n++ GaN and AlN layers. The gas used is a mixture of SF6 and O2. A 5 nm SiO2 is used as a gate dielectric and surface passivation to the device. The fabricated device shows a maximum drain current density of 800 mA/mm and a maximum peak transconductance of 135 mS/mm. The breakdown voltage of the device is 73 V. The measured contact resistance for the non-annealed and annealed Ohmic contact is between 5 to 10 Ω.mm and 0.4 to 0.6 Ω.mm, respectively. This indicates that the usage of heavily doped 5 nm n++ GaN cap layer helps in reducing the contact resistance. The results show the potential of the AlN/GaN MOSHEMT structure with a n++ GaN cap layer for future high frequency power application.

• Item Type: Articles
• Additional Information: Special Issue: InCAPE 2021
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wasige, Professor Edward and Dhongde, Aniket and Al-Khalidi, Dr Abdullah and Karami, Mr Kaivan and Taking, Dr Sanna and Ofiare, Dr Afesomeh
• Authors: Karami, K., Taking, S., Dhongde, A., Ofiare, A., Al-Khalidi, A., and Wasige, E.
• College/School: College of Science and Engineering > School of Engineering; College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: International Journal of Nanoelectronics and Materials
• Publisher: Universiti Malaysia Perlis (UniMAP)
• ISSN: 1985-5761
• Published Online: 01 December 2021
• Copyright Holders: Copyright © 2021 Universiti Malaysia Perlis (UniMAP)
• First Published: First published in International Journal of Nanoelectronics and Materials 14:45-51
• Publisher Policy: Reproduced with the permission of the publisher

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