Surface control and MBE growth diagram for homoepitaxy on single-crystal AlN substrates

Lee, Kevin; Cho, Yong-Jin; Schowalter, L. J.; Toita, Masato; Xing, Huili Grace; Jena, Debdeep

doi:10.1063/5.0010813

Cited by 35 publications

(24 citation statements)

References 35 publications

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“…This morphology with parallel straight atomic steps has been observed for the layers of binary and ternary (AlGa)N compounds, as well as in related heterostructures grown using both metal organic chemical vapor deposition (MOCVD) and plasma-assisted molecular beam epitaxy (PAMBE). [28,29] However, commercially these substrates cannot compete with cheap sapphire substrates commonly used for III-nitrides. In addition, AlGaN-based devices have a number of problems (point defects, quantumconfined Stark effect [QCSE], and transverse electric [TE]/ transverse magnetic [TM] polarization switching, described later) that cannot be completely solved even by the use of bulk AlN substrates.…”

Section: High Density Of Extended and Point Defectsmentioning

confidence: 99%

Monolayer‐Thick GaN/AlN Multilayer Heterostructures for Deep‐Ultraviolet Optoelectronics

Jmerik

Торопов

Davydov

et al. 2021

Physica Rapid Research Ltrs

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Recent progress in the development of monolayer (ML)‐thick GaN/AlN multilayer heterostructures for deep‐ultraviolet (UV) optoelectronics is reviewed. Analysis of both plasma‐assisted molecular beam epitaxy and metal–organic vapor phase epitaxy shows that extreme interface sharpness and sub‐ML accuracy in setting the layer thickness are attractive features of the former, whereas the lowest density of threading dislocations and wide possibilities for the implementation of various 2D growth mechanisms are the advantages of the latter. The structural properties of ML GaN/AlN heterostructures are evaluated not only by standard X‐ray diffraction and scanning transmission electron microscopy, but also by Raman spectroscopy. Theoretical and experimental studies of the optical properties of ML‐thick GaN/AlN quantum wells (QWs) reveal that quenching of the quantum‐confined Stark effect, suppression of transverse electric transverse magnetic polarization switching, as well as the excitonic nature of UV‐radiative recombination in ultrathin (1–2 ML) QWs ensure in such structures a high internal quantum yield of 75% for UV radiation at 235 nm at room temperature. The possibilities of using ML‐GaN/AlN heterostructures to fabricate UVC emitters of spontaneous and stimulated emissions in a wide range of output powers with various pumping techniques are considered, and the most important problems are formulated.

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Section: High Density Of Extended and Point Defectsmentioning

confidence: 99%

Monolayer‐Thick GaN/AlN Multilayer Heterostructures for Deep‐Ultraviolet Optoelectronics

Jmerik

Торопов

Davydov

et al. 2021

Physica Rapid Research Ltrs

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“…With the rising relevance of AlN as the platform for UV photonics and future RF electronics 8,28 , significant interest exists in using 2DEGs and 2DHGs on AlN to make RF p-channel 7,29 and n-channel transistors 30,31 and enable wide-bandgap RF CMOS type devices. Combining the results of this work with recent advancements in homoepitaxial growths of AlN 32,33 should enable fundamental scientific studies of 2DEGs and 2DHGs in such polar heterostructures and simultaneously enable significant technological advances.…”

Section: Discussionmentioning

confidence: 88%

High conductivity Polarization-induced 2D hole gases in Undoped GaN/AlN Heterojunctions enabled by Impurity Blocking Layers

Chaudhuri,

Chen,

Muller

et al. 2021

Preprint

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High-conductivity undoped GaN/AlN 2D hole gases (2DHGs), the p-type dual of the AlGaN/GaN 2D electron gases (2DEGs), have offered valuable insights into hole transport in GaN and enabled the first GaN GHz RF p-channel FETs. They are an important step towards high-speed and high-power complementary electronics with wide-bandgap semiconductors. These technologically and scientifically relevant 2D hole gases are perceived to be not as robust as the 2DEGs because structurally similar heterostructures exhibit wide variations of the hole density over ∆p s > 7 × 10 13 cm −2 , and low mobilities. In this work, we uncover that the variations are tied to undesired dopant impurities such as Silicon and Oxygen floating up from the nucleation interface. By introducing impurity blocking layers (IBLs) in the AlN buffer layer, we eliminate the variability in 2D hole gas densities and transport properties, resulting in a much tighter-control over the 2DHG density variations to ∆p s ≤ 1 × 10 13 cm −2 across growths, and a 3× boost in the Hall mobilities. These changes result in a 2-3× increase in hole conductivity when compared to GaN/AlN structures without IBLs.

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“…For sample A, no intentional in-situ cleaning was performed, whereas for sample B, Al-assisted surface cleaning was employed before the MBE growth. The Al-assisted surface cleaning consists of multiple cycles of Al adsorption and desorption, similar to earlier reports on Al-polar AlN substrates (19,20). The substrate was first heated up to a thermocouple temperature of 1060 °C without nitrogen gas flow.…”

Section: Resultsmentioning

confidence: 98%

Molecular beam homoepitaxy of N-polar AlN: enabling role of Al-assisted surface cleaning

Zhang¹,

Hayashi²,

Tohei³

et al. 2022

Preprint

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Surface control and MBE growth diagram for homoepitaxy on single-crystal AlN substrates

Cited by 35 publications

References 35 publications

Monolayer‐Thick GaN/AlN Multilayer Heterostructures for Deep‐Ultraviolet Optoelectronics

Monolayer‐Thick GaN/AlN Multilayer Heterostructures for Deep‐Ultraviolet Optoelectronics

High conductivity Polarization-induced 2D hole gases in Undoped GaN/AlN Heterojunctions enabled by Impurity Blocking Layers

Molecular beam homoepitaxy of N-polar AlN: enabling role of Al-assisted surface cleaning

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