Impact of pits formed in the AlN nucleation layer on buffer leakage in GaN/AlGaN high electron mobility transistor structures on Si (111)

Rathkanthiwar, S and Kalra, A and Remesh, N and Bardhan, A and Muralidharan, R and Nath, DN and Raghavan, S (2020) Impact of pits formed in the AlN nucleation layer on buffer leakage in GaN/AlGaN high electron mobility transistor structures on Si (111). In: Journal of Applied Physics, 127 (21).

PDF Jou_App_Phy_127_21_2020.pdf - Published Version Restricted to Registered users only Download (3MB) | Request a copy

Abstract

Limiting buffer layer current leakage is essential for the realization of high breakdown fields in GaN-on-Si high electron mobility transistors (HEMTs). In this report, we demonstrate the importance of controlling the surface morphology of the AlN nucleation layer (NL) in limiting this leakage. Testing on a self-consistent series of samples grown under two different AlN NL conditions revealed the presence of leakage paths within the epilayers grown using a single temperature AlN NL owing to the presence of surface pits. The introduction of a higher temperature AlN in the NL drastically reduced the pit density and led to a large reduction (>103) in the lateral and vertical buffer leakage in HEMT structures. Using conductive atomic force microscopy, secondary ion mass spectroscopy, and temperature-dependent carrier transport measurements, we confirm that these pits-which originate in the AlN NL, thread vertically, and propagate into the device structures- A re associated with leakage paths, thus reducing the field that can be dropped across the epilayers. This is explained by invoking preferential oxygen segregation at their side-facets. It is shown that when a pit-free surface is maintained, a vertical field of 1.6 MV/cm can be achieved for HEMTs. This study is expected to benefit the development of high-performance GaN HEMTs in moving toward the theoretical breakdown field of III-nitrides.

Item Type:	Journal Article
Publication:	Journal of Applied Physics
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright for this article belongs to American Institute of Physics.
Keywords:	Aluminum nitride; Atomic force microscopy; Buffer layers; Crystal atomic structure; Crystallization; Electron mobility; Epilayers; Gallium nitride; III-V semiconductors; Morphology; Nucleation; Power HEMT; Secondary ion mass spectrometry; Silicon; Surface morphology, AlN nucleation layers; Conductive atomic force microscopy; High breakdown fields; High electron mobility transistor (HEMT); High electron mobility transistor (HEMTs); Secondary ion mass spectroscopy; Temperature dependent; Transport measurements, High electron mobility transistors
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	06 Feb 2023 07:17
Last Modified:	06 Feb 2023 07:17
URI:	https://eprints.iisc.ac.in/id/eprint/79875

Actions (login required)

View Item