Shutter control method for control of Al contents in AlGaN quasi-ternary compounds grown by RF-MBE

Kikuchi, Akihiko; Yoshizawa, Masaki; Mori, Miyuki; Fujita, Nobuhiko; Kushi, Kouichi; Sasamoto, Hajime; Kishino, Katsumi

doi:10.1016/s0022-0248(98)00182-1

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…5) The GaN layers were grown by the shutter control method (Ga was supplied continuously but the nitrogen supply was interrupted periodically). 15,16) The RHEED pattern during the HT-AlN-NL growth was fuzzily spotty, but the HT-AlN-ILs on the GaN layers showed bright and sharp (1 × 1) streaks. During the GaN growth, the streak was dark due to the slight Ga-rich condition, but the streak became bright and sharp (1×1) when the Ga supply was stopped.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Crystal Quality of RF-Plasma-Assisted Molecular Beam Epitaxy Grown Ga-Polarity GaN by High-Temperature Grown AlN Multiple Intermediate Layers

Kikuchi

Yamada

Nakamura

et al. 2000

Jpn. J. Appl. Phys.

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The effects of high-temperature-grown AlN multiple intermediate layers (HT-AlN-MILs) on the crystal quality of Ga-polarity GaN layers grown on (0001) Al 2 O 3 substrates by molecular beam epitaxy using rf-plasma nitrogen source were investigated. The high-temperature-grown AlN intermediate layers (HT-AlN-ILs) with different thicknesses were found to play different roles in the improvement of crystal quality. The 8-nm-thick HT-AlN-ILs brought about improvement of electrical properties. On the other hand, the 2-nm-thick HT-AlN-ILs improved the surface morphology. The combination of these 8-nm-HT-AlN-ILs and 2-nm-HT-AlN-ILs improved both the electrical properties and the surface morphology concurrently.

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Section: Introductionmentioning

confidence: 99%

Improvement of Crystal Quality of RF-Plasma-Assisted Molecular Beam Epitaxy Grown Ga-Polarity GaN by High-Temperature Grown AlN Multiple Intermediate Layers

Kikuchi

Yamada

Nakamura

et al. 2000

Jpn. J. Appl. Phys.

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“…Prior to the MBE growth, the GaN templates were exposed to Ga beam at 300 o C, then the substrate temperature was ramped to 700 o C and the active nitrogen was irradiated to the substrate surface. In the growth process, the substrate temperature was set to be 720 o C. The AlN layers were grown by migration enhanced epitaxy (Al and nitrogen were alternatively supplied) [6] and the GaN layers were grown by the shutter control method (Ga was continuously supplied and nitrogen was periodically interrupted) [7]. The detailed structure of the two samples, DB-RTD and SLB-RTD, will be shown in the following sections.…”

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AlGaN Resonant Tunneling Diodes Grown by rf-MBE

Kikuchi

Bannai

Kishino

2001

phys. stat. sol. (a)

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Subject classification: 73.40.Kp; S7.14 AlGaN resonant tunneling diodes (RTD) have been successfully grown by molecular beam epitaxy. Two kinds of RTD samples were fabricated; one is a double barrier type RTD which has 1 nm AlN barriers and a 0.75 nm GaN well, and the other is a superlattice barrier type RTD which has six 1 nm AlN barriers and five 1 nm GaN wells. The negative differential resistance (NDR) effect in the current-voltage characteristics was clearly observed at room temperature. For the double barrier RTD sample, the NDR was observed at 2.4 V with a peak current density of 930 mA/cm 2 and a peak-to-valley ratio of 3.1. For the superlattice barrier RTD sample, the NDR was observed at 1.6 V. The peak current density and peak-to-valley ratio were 142 A/cm 2 and 9.7, respectively.Introduction The III-nitride material system has many attractive properties such as a large bandgap energy, large bandgap discontinuity, high peak electron velocity, high saturation electron velocity and higher thermal stability. Many studies on AlGaN based electrical devices have been reported on HEMT, FET, HBT, etc. From the point of view of large bandgap discontinuity of~1.95 eV (for AlN/GaN system), various quantum effect device applications are expected; such as resonant tunneling diodes (RTD) [1], intersubband transition near infrared optical devices [2] and so on. The RTD is attractive for high-frequency functional device applications. The large bandgap discontinuity requires monolayer-order thickness controllability and a smooth interface for the epitaxial growth. In this respect, molecular beam epitaxy (MBE) seems to be a suitable growth technique to realize a fine control of the nitride heterostructures. In fact, recently, very high two-dimensional electron gas mobility over 50000 cm 2 /Vs [3, 4] and near infrared intersubband transition [5] have been demonstrated by MBE grown AlGaN/GaN heterostructure.In this paper, we will descrive the first successful growth of AlN/GaN RTD by MBE using rf-plasma nitrogen source (rf-MBE). Two kinds of RTDs with different AlN barrier structures were adopted. One is conventional double barrier (DB) type, and the other is superlattice barrier (SLB) type. The current-voltage characteristics showed clear negative differential resistance (NDR) in both samples at room temperature. The structural dependence of peak current density and peak-to-vally current ratio of NDR will be described.

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“…Conventional MBE techniques for GaN growth use gallium metal or organic gallium as a source material. These techniques require a reaction between a gallium source and a nitrogen source on the substrate, for which excited nitrogen or ammonia is used as a nitrogen source [5][6][7][8]. Although the crystallization requires thermal energy, the synthesis reaction also requires a high temperature.…”

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confidence: 99%