Study of the impact of interface traps associated with SiN Xpassivation on AlGaN/GaN MIS-HEMTs

Baby, R and Venugopalrao, A and Chandrasekar, H and Raghavan, S and Rangarajan, M and Nath, DN (2022) Study of the impact of interface traps associated with SiN Xpassivation on AlGaN/GaN MIS-HEMTs. In: Semiconductor Science and Technology, 37 (3).

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Abstract

In this work, we show that a bilayer SiN x passivation scheme which includes a high-temperature annealed SiN x as gate dielectric, significantly improves both ON and OFF state performance of AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). Surface and bulk leakage paths were determined from devices with different SiN x passivation schemes. Temperature-dependent mesa leakage studies showed that the surface conduction could be explained using a 2D variable range hopping mechanism; this is attributed to the mid-gap interface states at the GaN(cap)/SiN x interface generated due to the Ga-Ga metal like bonding states. It was found that the high temperature annealed SiN x gate dielectric exhibited the lowest interface state density and a two-step C-V indicative of a superior quality SiN x /GaN interface as confirmed from conductance and capacitance measurements. High-temperature annealing helps form Ga-N bonding states, thus reducing the shallow metal-like interface states. MISHEMT measurements showed a significant reduction in gate leakage and a four-orders of magnitude improvement in the ON/OFF ratio while increasing the saturation drain current (I DS) by a factor of 2. Besides, MISHEMTs with two-step SiN x passivation exhibited a relatively flat transconductance profile, indicating lower interface states density. The dynamic R on with gate and drain stressing measurements also showed about 3 improvements in devices with bilayer SiN x passivation.

Item Type:	Journal Article
Publication:	Semiconductor Science and Technology
Publisher:	IOP Publishing Ltd
Additional Information:	The copyright for this article belongs to the IOP Publishing Ltd.
Keywords:	Aluminum gallium nitride; Annealing; Capacitance measurement; Drain current; Gallium nitride; Gate dielectrics; High electron mobility transistors; III-V semiconductors; Interface states; Metal insulator boundaries; Passivation; Silicon nitride; Wide band gap semiconductors, Bi-layer; Dynamic on-resistance; GaN HEMTs; High electron-mobility transistors; Highest temperature; Interfaces state; Metal-insulator-semiconductors; Off-state leakage; On-resistance; SiN x passivation, MIS devices
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	30 Jun 2022 05:39
Last Modified:	30 Jun 2022 05:39
URI:	https://eprints.iisc.ac.in/id/eprint/73796

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