Evidence of Carrier Localization in AlGaN/GaN‐Based UV Multiple Quantum Wells with Opposite Polarity Domains Provided by Nanoscale Imaging

Cui, Meiying; Guo, Wei; Xu, Houqiang; Jiang, Jie’an; Chen, Li; Mitra, Somak; Roqan, Iman S.; Jiang, Haibo; Li, Xiaohang; Ye, Jichun

doi:10.1002/pssr.202100035

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…For example, N-polar AlGaN DUV LEDs have better carrier injection efficiency and alleviated electron overflow than the Al-polar ones . N-polar AlGaN HEMTs are envisioned to have merits of high back-barrier, low ohmic contact resistivity, and flexible device scaling. − Moreover, the lateral-polarity structure, where N-polar and Al-polar domains are deposited periodically side by side in plane, shows great potential in fabricating DUV LEDs with higher radiation combination rate, and waveguides for generating second-harmonic . High-quality N-polar AlN templates are vital to achieve efficient N-polar Al-rich AlGaN-based devices due to the lack of native AlGaN substrates.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Zhang

Guo

Cai

et al. 2023

Crystal Growth & Design

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In this study, we demonstrated AlN films with unexpected N-polarity on Si-face 4H−SiC substrates using RF reactive magnetron sputtering and post high-temperature annealing (HTA). It is found that HTA-AlN sputtered with pure nitrogen or mixed gases of nitrogen and trace oxygen exhibits undoubtable N polarity, which appears to contradict the common assumption of Al-polar AlN on Si-face SiC. The interfacial studies of HTA-AlN sputtered with pure N 2 reveal that the naturally oxidized SiC surface induces the formation of Si−O�Al−N bonds rather than conventional Si�N−Al bonds, thereby causing N-polar AlN. Sputtering with the mixed gases results in 5 nm thick complex transition layers at the AlN/SiC interface, including two types of oxygen-participated energy-unstable inversion domain boundaries and multiple polarity inverted AlN layers. Compared to that sputtered with the mixed gases, the N-polar HTA-AlN film sputtered with pure nitrogen presents a smoother surface morphology for the absence of AlON islands and lower threading dislocation density due to closer X-ray rocking curve full widths at half-maximum for (0002) and (101̅ 2) reflections. This work proves a new approach to prepare high-quality N-polar AlN/SiC templates for Al-rich AlGaN-based N-polar optoelectronic and power devices.

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Section: Introductionmentioning

confidence: 99%

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Zhang

Guo

Cai

et al. 2023

Crystal Growth & Design

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Ferroelectric domain modulated AlGaN/GaN field effect transistor

Tang

Lü

Cong

et al. 2022

Applied Physics Letters

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A two-dimensional electron gas (2DEG) in (Al, Ga) N/GaN heterojunction (AlGaN/GaN) is a key factor that affects the performance of GaN-based high electron mobility transistor (HEMT) devices. Previous studies have shown that the ferroelectric polarization can effectively control the density of the 2DEG at the AlGaN/GaN interface; however, the correlation between two-dimensional distribution of ferroelectric polarization (i.e., ferroelectric domains) and its ability to confine the 2DEG is yet to be investigated. In this work, ferroelectric domain-induced modulation of the 2DEG in the AlGaN/GaN heterostructure was characterized using microscopic as well as local transport measurement techniques. The results suggest direct evidence for effective ferroelectric domain engineering in GaN HEMTs, as predicted by theoretical calculations. Additionally, a prototype device was fabricated, where gating was realized by utilizing the polarization of the ferroelectric domain. Considering the nonvolatile and reconfigurable advantages of a ferroelectric domain, the E-mode, D-mode, and even multi-channel output characteristics were realized in the same device by artificially engineered ferroelectric domain structures. These results offer a promising solution for the contradiction between the 2DEG density and gate controllability in GaN HEMTs, thereby showing a great potential of GaN radio frequency devices with further scaled gate lengths down to a few nanometers in the future.

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Self-powered ultraviolet photodiode based on lateral polarity structure GaN films

Mukhopadhyay

Pal

Narang

et al. 2021

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In this work, we report on a self-powered ultraviolet photodiode realized using lateral polarity structure (LPS) GaN films. The opposite nature of the polarization charge yields different barrier heights at the standard Ni/Au Schottky contact interface of N-polar and III-polar GaN films. As a result, a natural nonzero built-in potential is obtained in the LPS GaN photodiode, which showed photoresponsivity even at 0 V applied bias. The self-powered mechanism inside such an LPS GaN photodiode is discussed in detail by a combination of simulation prediction and experimental validation. Furthermore, a variation in the doping concentration of the adjacent III- and N-polar GaN domain is shown to improve the photoresponsivity compared to the conventional III-polar photodiode. Thus, this work validates that the LPS GaN photodiode is a promising candidate to realize self-powered operation and a general design rule for the photodiode with in-plane built-in potential.

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Evidence of Carrier Localization in AlGaN/GaN‐Based UV Multiple Quantum Wells with Opposite Polarity Domains Provided by Nanoscale Imaging

Cited by 3 publications

References 34 publications

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Unexpected Realization of N-Polar AlN Films on Si-Face 4H–SiC Substrates Using RF Sputtering and High-Temperature Annealing

Ferroelectric domain modulated AlGaN/GaN field effect transistor

Self-powered ultraviolet photodiode based on lateral polarity structure GaN films

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