Defect observations of Ni/AlGaN/GaN Schottky contacts on Si substrates using scanning internal photoemission microscopy

Shiojima, Kenji; Konishi, Hiroaki; Imadate, Hiroyoshi; Yamaoka, Yuya; Matsumoto, Kou; Egawa, Takashi

doi:10.7567/jjap.57.04fg07

Cited by 5 publications

(2 citation statements)

References 34 publications

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“…In general, electrical characterization of resistive regions is difficult, but SIPM is able to map them in two dimensions. Figure 22 shows SIPM measurements on AlGaN/GaN high electron mobility transistor (HEMT) wafers on a Si substrate (40). Typically, epitaxial growth of AlGaN/GaN HEMT structures has been performed on sapphire or SiC substrates, which are chemically stable during crystal growth.…”

Section: Two-dimensional Characterization Using Our Scanning Internal...mentioning

confidence: 99%

(Invited) Characterization of Metal/GaN Schottky Contacts - Review from the Early Days

Shiojima

2023

ECS Trans.

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This paper reviews innovation of metal/GaN contacts from the aspects of crystal quality, process technique, and basic understanding of the electrical characteristics. Five topics; (i) thermal degradation of refractory metal contacts, (ii) correlation between dislocations and electrical characteristics, (iii) exploring ideal metal/GaN interfaces by cleaving, surface treatment, and post metallization annealing, (iv) large-barrier p-GaN Schottky contacts by reducing Mg doping level, (v) two-dimensional characterization using our original method: scanning internal photoemission microscopy are described.

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Section: Two-dimensional Characterization Using Our Scanning Internal...mentioning

confidence: 99%

(Invited) Characterization of Metal/GaN Schottky Contacts - Review from the Early Days

Shiojima

2023

ECS Trans.

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“…Recently, as wide-bandgap semiconductor materials have been intensively studied for high-power RF and switching electron devices, we reconstructed SIPM for these by using visible lasers. We demonstrated two-dimensional (2-D) characterization of interfacial reaction and surface damages in SiC, GaN, and Oxide-semiconductor Schottky contacts (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). We also demonstrated that SIPM is available for semiconductor/semiconductor (S/S) hetero-interfaces and metal-insulator-semiconductor (MIS) interfaces (19,20).…”

Section: Introductionmentioning

confidence: 98%

(Invited) Two-Dimensional Characterization of Wide-Bandgap Materials and Contact Interfaces by Using Scanning Internal Photoemission Microscopy

Shiojima¹

2021

ECS Trans.

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Scanning internal photoemission spectroscopy has been developed to map the electrical characteristics of metal/semiconductor interfaces nondestructively. We conducted two-dimensional characterization of wide-bandgap Schottky contacts such as GaN, SiC, and oxide semiconductors. Our experimental demonstrations of the mapping characterization are reviewed from the aspects of (A) thermal degradation, (B) device degradation by applying highvoltage, (C) process-induced surface damages, (D) grain boundaries of semiconductors and printed metal particles, and (E) expansion to semiconductor/semiconductor and metal-insulator-semiconductor interfaces. This technique was confirmed to be useful for the development of the wide-bandgap-semiconductor high-power devices.

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Local bandgap narrowing in the forming state of threshold switching materials

Shiojima,

Kawai,

Kawasumi

et al. 2024

Applied Physics Letters

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Threshold switching (TS) materials, such as amorphous chalcogenide, have received significant attention for their application in storage class memory and in-memory computing. These materials contribute to efficient data processing and reduced power consumption in data centers. The initial switching process after fabricating a TS device, known as “forming,” has a profound impact on its subsequent TS behavior. However, it remains unclear how TS materials undergo changes in their atomic and electronic structures during the forming process. Consequently, the key factors that govern TS behavior remain obscure, necessitating a deeper understanding of the underlying physics behind TS phenomena. In this Letter, we investigated the forming state of the TS material AlTeN by combining scanning internal photoemission microscopy (SIPM) and ab initio calculations. Thanks to nondestructive evaluation by SIPM measurements, we observed local bandgap narrowing of AlTeN after its forming process. This is an experimental demonstration showing the presence of nuclei of the conductive filament formed in its ON state. Moreover, we conducted an ab initio calculation to reveal the origin of bandgap narrowing. We applied strong electrothermal stresses to the AlTeN model by ab initio molecular dynamics simulation with high electronic and lattice temperatures. By quenching from the electrothermal stress conditions, we reproduced an experimentally observed forming state with a narrowed bandgap. Analysis of the electronic structures of the forming state revealed that the origin of bandgap narrowing is the generation of the valence band top and conduction band bottom stemming from the increased homopolar bonds.

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Defect observations of Ni/AlGaN/GaN Schottky contacts on Si substrates using scanning internal photoemission microscopy

Cited by 5 publications

References 34 publications

(Invited) Characterization of Metal/GaN Schottky Contacts - Review from the Early Days

(Invited) Characterization of Metal/GaN Schottky Contacts - Review from the Early Days

(Invited) Two-Dimensional Characterization of Wide-Bandgap Materials and Contact Interfaces by Using Scanning Internal Photoemission Microscopy

Local bandgap narrowing in the forming state of threshold switching materials

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