Study of high quality AlN layers grown on Si(111) substrates by plasma-assisted molecular beam epitaxy

1997 ◽  
Vol 2 ◽  
Author(s):  
M. A. Sánchez-García ◽  
E. Calleja ◽  
E. Monroy ◽  
F. J. Sánchez ◽  
F. Calle ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Structural Quality ◽  
Half Maximum ◽  
High Quality ◽  
Force Microscopy ◽  
Aln Buffer ◽  
Xrd Techniques

High quality AlN layers with full widths at half maximum values of 10 arcmin and average surface roughness (rms) of 48Å were grown by molecular beam epitaxy on Si(111) substrates. A systematic study and optimization of the growth conditions was performed in order to use these AlN layers as buffers in the growth of GaN films. Atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques were employed to determine the surface and structural quality of the layers. Best AlN films were obtained at high substrate temperatures (Tsubs>900°C) and III/V ratios close to stoichiometry. Growth conditions with III/V ratios beyond stoichiometry (Al-rich) did not further improve the crystal quality. In these cases a higher substrate temperature is needed to prevent condensation of Al on the surface. GaN films with full width at half maximum of 10 arcmin and improved optical properties were grown on top of optimized AlN buffer layers.

Effect of V/III Ratio on the Properties of GaN Layers Grown by Molecular Beam Epitaxy Using NH3

1998 ◽  
Vol 512 ◽  
Author(s):  
N. Grandjean ◽  
M. Leroux ◽  
J. Massies ◽  
M. Mesrine ◽  
P. Lorenzini
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Buffer Layers ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Piezoelectric Field ◽  
Secondary Ion

ABSTRACTAmmonia as nitrogen precursor has been used to grow III-V nitrides by molecular beam epitaxy (MBE) on c-plane sapphire substrates. The efficiency of NH3 has been evaluated allowing the determination of the actual V/III flux ratio used during the GaN growth. The effects of the V/III ratio variation on the GaN layer properties have been investigated by photoluminescence (PL), Hall measurements, atomic force microscopy (AFM), and secondary ion mass spectroscopy (SIMS). It is found that a high V/III ratio leads to the best material quality. Optimized GaN thick buffer layers have been used to grow GaN/AlGaN quantum well (QW) heterostructures. Their PL spectra exhibit well resolved emission peaks for QW thicknesses varying from 3 to 15 monolayers. From the variation of the QW energies as a function of well width, a piezoelectric field of 450 kV/cm is deduced.

INFLUENCE OF Al MONOLAYERS ON THE PROPERTIES OF AlN LAYERS ON Si (111)

2009 ◽  
Vol 16 (01) ◽  
pp. 99-103 ◽  
Author(s):  
L. S. CHUAH ◽  
Z. HASSAN ◽  
H. ABU HASSAN
Keyword(s):  
Buffer Layers ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flat Surfaces ◽  
Gan On Si ◽  
Aln Buffer ◽  
Xrd Techniques ◽  
Substrate Temperatures

High-quality aluminum nitride ( AlN ) layers with full width at half maximum (FWHM) values of 11 arcmin were grown by plasma-assisted molecular-beam epitaxy on Si (111) substrates. AlN nucleation layers are being investigated for the growth of GaN on Si . Growth using AlN buffer layers leads to Al -polar films, with surfaces strongly dependent on the flux conditions used. Flat surfaces can be obtained by growing as Al -rich as possible, although Al droplets tend to form. Before starting the AlN growth, a few monolayers of Al are deposited on the substrate to avoid the formation of Si 3 N 4. X-ray diffraction (XRD) techniques were employed to determine the surface and structural quality of the layers. XRD revealed that monocrystalline AlN was obtained. Best AlN films were obtained at high substrate temperatures (875°C) and III/V ratios close to stoichiometry.

Effect of Buffer Design on AlGaN/AlN/GaN Heterostrucutres by MBE

2003 ◽  
Vol 798 ◽  
Author(s):  
Gon Namkoong ◽  
W. Alan ◽  
A. S. Brown ◽  
M. Losurdo ◽  
M. M. Giangregorio ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Buffer Layer ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Structural Quality ◽  
Epitaxial Layers ◽  
Etch Pit Density ◽  
Etch Pit ◽  
Sheet Charge ◽  
Aln Buffer

ABSTRACTThe effect of the buffer layers on the subsequent GaN epitaxial layers and electrical properties of AlGaN/AlN/GaN heterojunction structures nitrided at various temperatures was investigated. For AlN buffer layers, two different growth conditions of AlN buffer layers were introduced to avoid Al droplets. We found that etch pit density and structural quality of GaN epitaxial layer strongly depends on the growth conditions of AlN buffer layers. When using a double buffer layer (low temperature GaN on high temperature AlN) for 200 °C nitridation, the etch pit density was measured to high 107 cm-2 in GaN epitaxial layers. Furthermore, we observed that electrical properties of AlGaN/AlN/GaN heterostructures depend on growth conditions of buffer layers and nitridation temperatures. The mobility in Al0.33Ga0.67N/AlN/GaN structures grown on single AlN buffer layers for 200 °C nitridation were 1300 cm2/Vs at a sheet charge of 1.6×1013 cm-2. Using the double buffer layer for 200 °C nitridation, the mobility increased to 1587 cm2/Vs with a sheet charge of 1.25×1013 cm-2.

scholarly journals High carrier mobility in single-crystal PtSe2 grown by molecular beam epitaxy on ZnO(0001)

2D Materials ◽  
2021 ◽  
Author(s):  
Frédéric Bonell ◽  
Alain Marty ◽  
Céline Vergnaud ◽  
Vincent Consonni ◽  
Hanako Okuno ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Mobility ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
High Carrier Mobility ◽  
Insulating Substrates

Abstract PtSe2 is attracting considerable attention as a high mobility two-dimensional material with envisioned applications in microelectronics, photodetection and spintronics. The growth of high quality PtSe2 on insulating substrates with wafer-scale uniformity is a prerequisite for electronic transport investigations and practical use in devices. Here, we report the growth of highly oriented few-layers PtSe2 on ZnO(0001) by molecular beam epitaxy. The crystalline structure of the films is characterized with electron and X-ray diffraction, atomic force microscopy and transmission electron microscopy. The comparison with PtSe2 layers grown on graphene, sapphire, mica, SiO2 and Pt(111) shows that among insulating substrates, ZnO(0001) yields films of superior structural quality. Hall measurements performed on epitaxial ZnO/PtSe2 with 5 monolayers of PtSe2 show a clear semiconducting behaviour and a high mobility in excess of 200 cm2V-1s-1 at room temperature and up to 447 cm2V-1s-1 at low temperature.

scholarly journals Separation of AlN layers from silicon substrates by KOH etching

2021 ◽  
Vol 2086 (1) ◽  
pp. 012037
Author(s):  
K Yu Shubina ◽  
D V Mokhov ◽  
T N Berezovskaya ◽  
E V Pirogov ◽  
A V Nashchekin ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Surface Damage ◽  
Vapour Phase ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
Vapour Phase Epitaxy ◽  
Aln Buffer ◽  
Cr Film ◽  
Koh Etching

Abstract In this work, the AlN/Si(111) epitaxial structures grown consistently by plasma assisted molecular beam epitaxy (PA MBE) and hydride vapour phase epitaxy (HVPE) methods were studied. The PA MBE AlN buffer layers were synthesized via coalescence overgrowth of self-catalyzed AlN nanocolumns on Si(111) substrates and were used as templates for further HVPE growth of thick AlN layer. It was shown that described approaches can be used to obtain AlN layers with sufficiently smooth morphology. It was found that HVPE AlN inherited crystallographic polarity of the AlN layer grown by PA MBE. It was demonstrated that the etching of such AlN/Si(111) epitaxial structures results in partial separation of the AlN epilayers from the Si(111) substrate and allows to form suspended structures. Moreover, the avoidance of surface damage and backside overetching was achieved by use thin Cr film as surface protective coating and by increasing the layer thickness accordingly.

scholarly journals Molecular Beam Epitaxy of High Quality InGaN Alloys Using Ammonia: Optical and Structural Properties

1999 ◽  
Vol 4 (S1) ◽  
pp. 333-338
Author(s):  
Nicolas Grandjean ◽  
Jean Massies ◽  
Mathieu Leroux ◽  
Marguerite Laügt ◽  
Philippe Vennéguès ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Structural Properties ◽  
Molecular Beam ◽  
Stokes Shift ◽  
Growth Conditions ◽  
Structural Quality ◽  
Luminescence Spectra ◽  
Near Band Edge ◽  
Flat Surfaces

The growth of InGaN layers was carried out by molecular beam epitaxy (MBE). The nitrogen precursor was ammonia. The optical and structural properties of the InGaN layers have been investigated by transmission electron microscopy (TEM), x-ray diffraction (XRD) and photoluminescence (PL). For optimized growth conditions, the PL spectrum of InGaN (x=0.1) alloy is narrow (FWHM ≤ 50 meV) and the Stokes shift measured by PL excitation is weak (<50 meV), i.e. near band edge transitions are observed. Under these conditions, flat surfaces can be obtained, and InGaN/GaN quantum wells (QWs) with sharp interfaces can be grown. On the other hand, when growth conditions depart from a narrow optimum window, the structural quality of the samples strongly degrade, whereas the luminescence spectra are dominated by deep levels, exhibiting a strong Stokes shift. MBE grown light emitting diodes (LEDs) using InGaN/GaN QWs have been fabricated. Their electroluminescence (EL) peaks at 440 nm at 300K.

Indium Gallium Nitride on Germanium by Molecular Beam Epitaxy

2011 ◽  
Vol 1324 ◽  
Author(s):  
R.R. Lieten ◽  
W.-J. Tseng ◽  
M. Leys ◽  
J.-P. Locquet ◽  
J. Dekoster
Keyword(s):  
Molecular Beam ◽  
Growth Parameters ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Nitrogen Supply ◽  
Buffer Layers ◽  
Crystal Quality ◽  
Structural Quality ◽  
Nitride Layers ◽  
Ingan Alloys

ABSTRACTIndium containing III-Nitride layers are predominantly grown by heteroepitaxy on foreign substrates, most often Al2O3, SiC and Si. We have investigated the epitaxial growth of InxGa1-xN (InGaN) alloys on Ge substrates. First we looked at the influence of buffer layers between the InGaN and Ge substrate. When applying a high temperature (850 °C) GaN buffer, the InGaN showed superior crystal quality. Furthermore the influence of growth parameters on the structural quality and composition of InGaN layers has been looked into. For a fixed gallium and nitrogen supply, the indium beam flux was increased incrementally. For both nitrogen- as well as for metal (Ga + In) rich growth conditions, the In incorporation increases for increasing In flux. However, for metal rich growth conditions, segregation of metallic In is observed. An optimum in crystal quality is obtained for a metal:nitrogen flux ratio close to unity. The XRD FWHM of the GaN (0002) reflection increases significantly after InGaN growth. Apparently the presence of indium deteriorates the GaN buffer during InGaN growth. The mechanism of the effect is not known yet.

Fabrication and characterization of ZnMgO nanowalls grown on 4H-SiC by molecular beam epitaxy

2019 ◽  
Vol 52 (1) ◽  
pp. 168-170
Author(s):  
Mieczyslaw A. Pietrzyk ◽  
Aleksandra Wierzbicka ◽  
Marcin Stachowicz ◽  
Dawid Jarosz ◽  
Adrian Kozanecki
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optoelectronic Devices ◽  
Growth Conditions ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fabrication And Characterization

Control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic devices. This paper reports the growth conditions and structural properties of ZnMgO nanowalls grown on the Si face of 4H-SiC substrates by molecular beam epitaxy without catalysts and buffer layers. Images from scanning electron microscopy revealed that the ZnMgO nanowalls are arranged in parallel rows following the stripe morphology of the SiC surface, and their thickness is around 15 nm. The crystal quality of the structures was evaluated by X-ray diffraction measurements.

Study of Interface Properties of InN and InN-Based Heterostructures by Molecular Beam Epitaxy

2001 ◽  
Vol 693 ◽  
Author(s):  
Hai Lu ◽  
William J. Schaff ◽  
Lester F. Eastman ◽  
Colin Wood
Keyword(s):  
Molecular Beam Epitaxy ◽  
Film Thickness ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Growth Conditions ◽  
High Energy ◽  
Near Surface ◽  
Low Leakage ◽  
Sheet Charge ◽  
Aln Buffer

AbstractIn this work, we prepared epitaxial InN on (0001) sapphire with an AlN or GaN buffer layer by molecular beam epitaxy (MBE). A series of samples were grown with different thickness under the optimized growth conditions. Films were characterized by x-ray diffraction (XRD), reflective high-energy electron diffraction (RHEED), atomic-force microscopy (AFM), transmission electron microscopy (TEM) and Hall measurements. By extrapolating the fitted curve of sheet carrier density vs. film thickness to zero film thickness, a strong residual sheet charge was derived, which may be located at the interface between the buffer layer and the InN film, or at the near-surface. It was found that for InN film on AlN buffer, the residual sheet charge is about 4.3×1013 cm-2, while for InN films on GaN buffer, the residual sheet charge is about 2.5×1013 cm-2. At present, we tentatively believe that the residual charge is surface charge accumulation similar to what is observed at the InAs surface. InN samples with Hall mobility beyond 1300 cm2/Vs and carrier concentration below 2×1018 cm-3 were routinely achieved in this study.The first study on InN-based FET structures was performed. Amorphous AlN was used as the barrier material, which was prepared by migration enhanced epitaxy (MEE) at low growth temperature. It was found that the surface morphology is improved after an AlN barrier layer is added to InN. Hg was used as a back-to-back Schottky metallization. Very low leakage current and weak rectifying behavior were observed.

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