Control of Metal‐Rich Growth for GaN/AlN Superlattice Fabrication on Face‐to‐Face‐Annealed Sputter‐Deposited AlN Templates

Mokutani, Naoya; Deura, Momoko; Mouri, Shinichiro; Shojiki, Kanako; Xiao, Shengqiang; Miyake, Hideto; Araki, Tsutomu

doi:10.1002/pssb.202300061

Cited by 3 publications

(4 citation statements)

References 35 publications

(40 reference statements)

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“…Recently (in 2023), two research groups using PA MBE technology have joined the study of ML-thick GaN/AlN MQW structures emitting in the UVC range with e-beam pumping [ 115 , 116 ]. The first of them, headed by Daudin, is the leading scientific group that has developed a basic understanding of the PA MBE growth kinetics of III-N layers and associated heterostructures [ 117 , 118 ].…”

Section: Main Results Of Uvc Emission Using Electron Beam Pumpingmentioning

confidence: 99%

“…However, it should be noted that at energies above 20 keV, an ditional long-wavelength peak appeared at 340 nm, which was associated with the etration of a high-energy e-beam into the AlN buffer layer, in which it excites defe radiation (associated with carbon atoms and other defects). Recently (in 2023), two research groups using PA MBE technology have joined the study of ML-thick GaN/AlN MQW structures emitting in the UVC range with e-beam pumping [115,116]. The first of them, headed by Daudin, is the leading scientific group that has developed a basic understanding of the PA MBE growth kinetics of III-N layers and associated heterostructures [117,118].…”

Section: Medium-power Uvc Emitters (Up To 1 W)mentioning

confidence: 99%

“…Their emission consists of sharp lines extending up to 215 nm near the edge of the AlN band, as shown in Figure 24. In contrast, Araki's group grew a GaN/AlN superlattice with a well thickness estimated at 1.1-1.4 ML, using PA MBE with metal-rich growth conditions for both group III atoms, which provided an atomically flat AlN surface and abrupt interfaces in these heterostructures [116]. Subsequently, excess metals were eliminated by the so-called method of droplet elimination by radical beam irradiation for AlN (originally, this method was developed by this group for InN [121]) and growth interruptions for GaN.…”

Section: Medium-power Uvc Emitters (Up To 1 W)mentioning

confidence: 99%

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Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

2023

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Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230–280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1−xN/AlyGa1−yN (x = 0–0.5, y = 0.6–1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer’s (1 ML~0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.

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Section: Main Results Of Uvc Emission Using Electron Beam Pumpingmentioning

confidence: 99%

Section: Medium-power Uvc Emitters (Up To 1 W)mentioning

confidence: 99%

Section: Medium-power Uvc Emitters (Up To 1 W)mentioning

confidence: 99%

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Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

2023

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“…In contrast, Araki's group grew a GaN/AlN superlattice with a well thickness estimated at 1.1-1.4ML using PA MBE with metal-rich growth conditions for both group III atoms, which provided atomically flat AlN surface and abrupt interfaces in these heterostructures [116]. Subsequently, excess metals were eliminated by so-called method of droplet elimination by radical beam irradiation for AlN (originally this method was developed by this group for InN [117]) and growth interruptions for GaN.…”

Section: Uvc-emitters Pumped By Thermionic E-gunsmentioning

confidence: 99%

Electron-Beam Pumped UVC-Emitters Based on (Al, Ga)N Material System

Jmerik¹,

Kozlovsky²,

Wang³

2023

Preprint

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Powerful emitters of the ultraviolet C (UVC) light in the wavelength range of 230-280nm are necessary for the development of effective and safe optical disinfection technologies, high-sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers such UVC-emitters with electron-beam pumping of heterostructures with quantum wells in the (Al,Ga)N material system. The important advantages of these emitters include the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells AlxGa1-xN/AlyGa1-yN (x = 0 − 0.5, y = 0.6 − 1) fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional(2D) quantum disks GaN/AlN with a monolayer (1ML ~ 0.25nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and a high output UVC-optical powers.

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GaN thickness dependence of GaN/AlN superlattices on face-to-face-annealed sputter-deposited AlN templates

Deura,

Mokutani,

Wada

et al. 2024

Journal of Applied Physics

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Recently, deep-ultraviolet (DUV) light-emitting devices have attracted attention for various applications. GaN/AlN superlattices have emerged as a promising alternative for achieving high-efficiency DUV emission. To fabricate superlattices with high crystal quality and abrupt interfaces, we have utilized face-to-face-annealed sputter-deposited AlN template substrates characterized by a flat surface and low dislocation density. Furthermore, radio-frequency plasma-assisted molecular beam epitaxy with in situ reflection high-energy electron diffraction monitoring was employed for the growth process. The growth of the superlattices follows a specific sequence. Step 1: AlN growth, Step 2: conversion of Al droplets to AlN, Step 3: GaN growth, and Step 4: evaporation of Ga droplets. This study explored the impact of GaN thickness on the GaN/AlN superlattice. The GaN thickness was linearly controlled by changing the duration of Step 3. This approach allowed for the growth of a flat GaN layer up to 1 monolayer (ML) and achieved superlattices with abrupt interfaces. Single-peak cathodoluminescence (CL) emission at 240–245 nm was observed from the superlattices, with the peak shift toward longer wavelengths as the GaN thickness increased. In contrast, quantum dot-like GaN islands were generated with a thickness of over 1 ML, induced by compressive strain. Superlattices with thicker GaN exhibited broad CL emission with multiple peaks. However, the AlN barrier layer reduced the surface roughness and maintained abrupt interfaces within the superlattices. Therefore, to obtain sharp single-peak UV emission from GaN/AlN superlattices, the growth sequence should be controlled to obtain flat GaN layers without dots.

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Control of Metal‐Rich Growth for GaN/AlN Superlattice Fabrication on Face‐to‐Face‐Annealed Sputter‐Deposited AlN Templates

Cited by 3 publications

References 35 publications

Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

Electron-Beam Pumped UVC-Emitters Based on (Al, Ga)N Material System

GaN thickness dependence of GaN/AlN superlattices on face-to-face-annealed sputter-deposited AlN templates

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