Growth and Polarity Control of GaN and AlN on Carbon-face SiC by Metalorganic Vapor Phase Epitaxy

Fu, Y.; Ni, X.; Xie, J.; Bıyıklı, Necmi; Fan, Qian; Chevtchenko, Serguei; Özgür, Ü.; Morkoç̌, H.; Ke, You; Devaty, Robert P.; Choyke, W. J.; Inoki, C. K.; Kuan, T. S.

doi:10.1557/proc-0955-i07-37

Cited by 4 publications

(11 citation statements)

References 5 publications

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“…Previously, it was reported that a pre-flow of metal precursors (e.g. trimethylaluminum (TMAl), Al(CH 3 ) 3 , trimethylgallium (TMGa), Ga(CH 3 ) 3 ) or a low V/III (NH 3 /TMAl)-ratio flow [68,71] would result in metal-polarity layers on carbon-face (C-face) SiC substrates instead of expected N-polar layers. Polarity inversion from metal-polar to N-polar or mixed polarity could be triggered by e.g., substrate treatment or deposition of a low-temperature buffer layer [72].…”

Section: History and Challengesmentioning

confidence: 99%

“…Another major challenge of N-polar III-nitride epitaxy is polarity inversion. It was reported that the polarities of GaN and AlN layers were highly dependent on the pretreatment of C-face SiC substrates [71]. A pre-flow of TMAl on the surface of C-face SiC substrate before AlN nucleation layer growth, or a very low NH 3 /TMAl ratio at the initial growth stage of AlN result results in inversion to aluminum-polar (Al-polar) AlN or Ga-polar GaN.…”

Section: Mocvd Of N-polar Aln and Gan Layersmentioning

confidence: 99%

“…A pre-flow of TMAl on the surface of C-face SiC substrate before AlN nucleation layer growth, or a very low NH 3 /TMAl ratio at the initial growth stage of AlN result results in inversion to aluminum-polar (Al-polar) AlN or Ga-polar GaN. This effect is attributed to the formation of aluminum (Al) adlayers [71].…”

Section: Mocvd Of N-polar Aln and Gan Layersmentioning

confidence: 99%

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Hot-wall MOCVD of N-polar group-III nitride materials

Zhang

2021

Linköping Studies in Science and Technology. Licentiate Thesis

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Group III-Nitride semiconductors: indium nitride (InN), gallium nitride (GaN), aluminum nitride (AlN) and their alloys continue to attract significant scientific interest due to their unique properties and diverse applications in photonic and electronic applications.Group-III nitrides have direct bandgaps which cover the entire spectral range from the infrared (InN) to the ultraviolet (GaN) and to the deep ultraviolet (AlN). This makes III-nitride materials suitable for high-efficient and energy-saving optoelectronic devices, such as light-emitting diodes (LEDs) and laser diodes (LDs). The Nobel Prize in Physics 2014 was awarded for the invention of efficient GaN blue LEDs, which further accelerated the research in the field of group III-nitride materials. GaN and related alloys are also suitable for high-temperature, high-power and high-frequency electronic devices with performance that cannot be delivered by other semiconductor technologies such as silicon (Si) and gallium arsenide (GaAs). For example, GaN-based high electron mobility transistors (HEMTs) have been widely adopted for radio frequency (RF) communication and power amplifiers, high-voltage power switches in radars, satellites, and wireless base stations for 5G.Recently, nitrogen (N)-polar group-III nitrides have drawn much attention due to their advantages over their metal-polar counterparts in e.g. HEMTs. These include feasibility to fabricate ohmic contacts with low resistance, an enhanced carrier confinement with a natural back barrier, and improved device scalability. Despite intensive research, the growth of micrometer-thick high-quality N-polar GaN based materials remains challenging.One of the major problems to develop device-quality N-polar nitrides is the high surface roughness, which results from the formation of hexagonal hillocks or step-bunching.Another significant hurdle is the unintentional polarity inversion, which reduces the crystalline quality and prohibits device fabrication.This licentiate thesis focuses on the development of N-polar AlN and GaN heterostructures on SiC substrates for HEMT RF applications. The overall aim is to exploit the advantages of the hot-wall MOCVD concept to grow high-quality N-polar HEMT structures for higher operational frequencies and improved device performance. In order to achieve this goal, special effort is dedicated to understanding the effects of growth conditions and substrate orientation on the structural properties and polarity of AlN, GaN and AlGaN grown by hot-wall MOCVD. N-polar AlN nucleation layers (NLs) with layer by layer growth mode and step-flow growth mode can be achieved on on-axis and 4 • offaxis SiC (0001), respectively, by carefully controlling V/III ratio and growth temperature. Utilizing scanning transmission electron microscopy (STEM) we have established a comprehensive picture of the atomic arrangements, local polarity and polarity evolution in AlN, Mao, my KING, thank you for your endless support and love. You are also a super father! We are all happy under your rule :) Anna...

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Section: History and Challengesmentioning

confidence: 99%

Section: Mocvd Of N-polar Aln and Gan Layersmentioning

confidence: 99%

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Hot-wall MOCVD of N-polar group-III nitride materials

Zhang

2021

Linköping Studies in Science and Technology. Licentiate Thesis

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“…20 Nitrogen-rich growth conditions with a high V/III ratio were claimed to be required to realize N-polar III-nitride layers. 18,19 Furthermore, a distinct unintentional impurity incorporation of oxygen, carbon, and hydrogen in N-polar GaN layers was reported. 22 In our recent study, a three-dimensional (3D) growth mode of N-polar AlN NLs on SiC (0001̅ ) was identified as the likely cause for the observed polarity inversion.…”

Section: ■ Introductionmentioning

confidence: 99%

“…For instance, for metal− organic chemical vapor deposition (MOCVD) growth on Cface SiC substrates, where AlN nucleation layers (NLs) were deposited using a low V/III ratio, spontaneous polarity inversion was observed in N-polar AlN and GaN layers. 18,19 The preflow of trimethylaluminum (TMAl) for surface treatment of C-face SiC substrates was found to result in metal-polar instead of N-polar material. 20 Nitrogen-rich growth conditions with a high V/III ratio were claimed to be required to realize N-polar III-nitride layers.…”

Section: ■ Introductionmentioning

confidence: 99%

Polarity Control by Inversion Domain Suppression in N-Polar III-Nitride Heterostructures

Zhang

Persson

Chen

et al. 2023

Crystal Growth & Design

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Nitrogen-polar III-nitride heterostructures offer advantages over metal-polar structures in high frequency and high power applications. However, polarity control in III-nitrides is difficult to achieve as a result of unintentional polarity inversion domains (IDs). Herein, we present a comprehensive structural investigation with both atomic detail and thermodynamic analysis of the polarity evolution in low- and high-temperature AlN layers on on-axis and 4° off-axis carbon-face 4H-SiC (0001̅) grown by hot-wall metal organic chemical vapor deposition. A polarity control strategy has been developed by variation of thermodynamic Al supersaturation and substrate misorientation angle in order to achieve the desired growth mode and polarity. We demonstrate that IDs are completely suppressed for high-temperature AlN nucleation layers when a step-flow growth mode is achieved on the off-axis substrates. We employ this approach to demonstrate high quality N-polar epitaxial AlGaN/GaN/AlN heterostructures.

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Polarity control and fabrication of lateral polarity structures of III-nitride thin films and devices: progress and prospects

Guo

Chen

et al. 2020

J. Phys. D: Appl. Phys.

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Due to their non-centrosymmetric crystal orientation, wurtzite III-nitride crystals have two distinct orientations, i.e. III-polar and N-polar along the c-axis. Extensive effort has been devoted to polarity control and the characterization of III-nitride thin films. Both III-polar and N-polar films possess some unique features. By taking full advantage of both III and N-polar domains in a single structure, a lateral polarity structure (LPS), where III-polar and N-polar domains are grown side-by-side simultaneously on the wafer, has attracted great interest. In this review, recent progress in the design and fabrication of III-nitride LPS on various substrates is summarized. The structural, optical and electronic properties of III-nitride thin films incorporating LPS are discussed, with special attention paid to the interface between adjacent domains. Various techniques to qualitatively and quantitatively identify the polarity domains are provided, and their applications in optoelectronic and electronic devices including light-emitting-diodes, nonlinear frequency doubling waveguides, Schottky-barrier-diodes, etc, are intensively elaborated on. Finally, challenges related to the development of LPS-based devices and future perspectives are presented.

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Growth and Polarity Control of GaN and AlN on Carbon-face SiC by Metalorganic Vapor Phase Epitaxy

Cited by 4 publications

References 5 publications

Hot-wall MOCVD of N-polar group-III nitride materials

Hot-wall MOCVD of N-polar group-III nitride materials

Polarity Control by Inversion Domain Suppression in N-Polar III-Nitride Heterostructures

Polarity control and fabrication of lateral polarity structures of III-nitride thin films and devices: progress and prospects

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