7577. Formation of aluminium nitride films on GaAs(110) at room temperature by reactive molecular-beam epitaxy: X-ray and soft X-ray photo-emission spectroscopy

Origin of ultraviolet (UV) luminescence from bulk ZnO has been investigated with the help of photoluminescence (PL) measurements. Thin films of ZnO having 52%, 53% and 54% of Zn-contents were prepared by means of molecular beam epitaxy (MBE). We observed a dominant UV line at 3.28 eV and a visible line centered at 2.5 eV in the PL spectrum performed at room temperature. The intensity of UV line has been found to depend upon the Zn percentage in the ZnO layers. Thereby, we correlate the UV line in our samples with the Zn-interstitials-bound exciton (Zni-X) recombination. The results obtained from, x-ray diffraction, the energy dispersive X-ray spectrum (EDAX) and Raman spectroscopy supported the PL results.

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Sb2Te3 and Bi2Te3 Thin Films Grown by Molecular Beam Epitaxy at Room Temperature

MRS Proceedings ◽

10.1557/opl.2011.1251 ◽

2011 ◽

Vol 1329 ◽

Cited By ~ 2

Author(s):

Z. Aabdin ◽

M. Winkler ◽

D. Bessas ◽

J. König ◽

N. Peranio ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Molecular Beam Epitaxy ◽

Charge Carrier ◽

Power Factor ◽

Carrier Mobility ◽

Room Temperature ◽

Molecular Beam ◽

Charge Carrier Mobility ◽

X Ray

ABSTRACTNano-alloyed p-type Sb2Te3 and n-type Bi2Te3 thin films were grown on SiO2/Si and BaF2 substrates by molecular beam epitaxy (MBE) in two steps: (i) Repeated deposition of five-layer stacks with sequence Te-X-Te-X-Te (X = Sb or Bi) with elemental layer thicknesses of 0.2 nm on substrates at room temperature, (ii) annealing at 250 °C for two hours at which phase formation of Sb2Te3 or Bi2Te3 occurred. The room temperature MBE deposition method reduces surface roughness, allows the use of non lattice-matched substrates, and yields a more accurate and easier control of the Te content compared to Bi2Te3 thin films, which were epitaxially grown on BaF2 substrates at 290 °C. X-ray diffraction revealed that the thin films were single phase, poly-crystalline, and textured. The films showed grain sizes of 500 nm for Sb2Te3 and 250 nm for Bi2Te3, analyzed by transmission electron microscopy (TEM). The in-plane transport properties (thermopower S, electrical conductivity σ, charge carrier density n, charge carrier mobility μ, power factor S2σ) were measured at room temperature. The nano-alloyed Sb2Te3 thin film revealed a remarkably high power factor of 29 μW cm-1 K-2 similar to epitaxially grown Bi2Te3 thin films and Sb2Te3 single crystalline bulk materials. This large power factor can be attributed to a high charge carrier mobility of 402 cm2 V−1 s-1 similar to high-ZT Bi2Te3/Sb2Te3 superlattices. However, for the nano-alloyed Bi2Te3 thin film a low power factor of 8 μW cm−1 K-2 and a low charge carrier mobility of 80 cm2 V−1 s−1 were found. Detailed microstructure and phase analyses were carried out by energy-filtered TEM in cross-sections. Quantitative chemical analysis by energy-dispersive x−ray spectroscopy (EDS) was also applied. In Bi2Te3 thin films, few nanometer thick Bi-rich blocking layers at grain boundaries and Te fluctuations by 1.3 at.% within the grains were observed. The small charge carrier densities are explained by a reduced antisite defect density due to the low temperatures to which the thin films were exposed during annealing.

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Room-temperature ferromagnetism in (Mn, N)-codoped TiO2 films grown by plasma assisted molecular beam epitaxy

Journal of Applied Physics ◽

10.1063/1.3006135 ◽

2008 ◽

Vol 104 (9) ◽

pp. 093914 ◽

Cited By ~ 9

Author(s):

X. Y. Li ◽

S. X. Wu ◽

L. M. Xu ◽

Y. J. Liu ◽

X. J. Xing ◽

...

Keyword(s):

Molecular Beam Epitaxy ◽

Room Temperature ◽

Molecular Beam ◽

Room Temperature Ferromagnetism ◽

Tio2 Films ◽

Codoped Tio2

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Optical and structural prorerties of InAs epilayer on graded InGaAs

MRS Proceedings ◽

10.1557/proc-696-n3.10 ◽

2001 ◽

Vol 696 ◽

Author(s):

Gu Hyun Kim ◽

Jung Bum Choi ◽

Joo In Lee ◽

Se-Kyung Kang ◽

Seung Il Ban ◽

...

Keyword(s):

Molecular Beam Epitaxy ◽

Residual Strain ◽

Molecular Beam ◽

Lattice Mismatch ◽

Peak Position ◽

Excitation Intensity ◽

Total Thickness ◽

Ingaas Layer ◽

X Ray Diffraction ◽

X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

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X-Ray Diffraction Study of Rare Earth Epitaxial Structures Grown by MBE onto (111) GaAs

MRS Proceedings ◽

10.1557/proc-151-277 ◽

1989 ◽

Vol 151 ◽

Author(s):

W. R. Bennett ◽

R. F. C. Farrow ◽

S. S. P. Parkin ◽

E. E. Marinero

Keyword(s):

Rare Earth ◽

Molecular Beam Epitaxy ◽

Rare Earth Metal ◽

Molecular Beam ◽

Earth Metal ◽

Magnetic Ordering ◽

Metal Films ◽

X Ray Diffraction ◽

X Ray ◽

Strain Components

ABSTRACTWe report on the new epitaxial system LaF3/Er/Dy/Er/LaF3/GaAs (111) grown by molecular beam epitaxy. X-ray diffraction studies have been used to determine the epitaxial relationships between the rare earths, the LaF3 and the substrate. Further studies of symmetric and asymmetric reflections yielded the in-plane and perpendicular strain components of the rare earth layers. Such systems may be used to probe the effects of magnetoelastic interactions and dimensionality on magnetic ordering in rare earth metal films and multilayers.

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A Study on the Growth of Cubic GaN Films Using an AlGaAs Buffer Layer Grown on GaAs (100) by Plasma-Assisted Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-639-g3.46 ◽

2000 ◽

Vol 639 ◽

Author(s):

Ryuhei Kimura ◽

Kiyoshi Takahashi ◽

H. T. Grahn

Keyword(s):

Molecular Beam Epitaxy ◽

Buffer Layer ◽

Molecular Beam ◽

High Energy ◽

Rf Plasma ◽

Cubic Phase ◽

X Ray Diffraction ◽

X Ray ◽

Cubic Gan

ABSTRACTAn investigation of the growth mechanism for RF-plasma assisted molecular beam epitaxy of cubic GaN films using a nitrided AlGaAs buffer layer was carried out by in-situ reflection high energy electron diffraction (RHEED) and high resolution X-ray diffraction (HRXRD). It was found that hexagonal GaN nuclei grow on (1, 1, 1) facets during nitridation of the AlGaAs buffer layer, but a highly pure, cubic-phase GaN epilayer was grown on the nitrided AlGaAs buffer layer.

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Properties of Epitaxial SrTiO3 Thin Films Grown on Silicon by Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-567-427 ◽

1999 ◽

Vol 567 ◽

Cited By ~ 23

Author(s):

Z. Yu ◽

R. Droopad ◽

J. Ramdani ◽

J.A. Curless ◽

C.D. Overgaard ◽

...

Keyword(s):

Thin Films ◽

Molecular Beam Epitaxy ◽

Molecular Beam ◽

High Energy ◽

State Density ◽

Unit Cell ◽

Ex Situ ◽

Silicon Oxide Layer ◽

Single Crystalline ◽

X Ray

ABSTRACTSingle crystalline perovskite oxides such as SrTiO3 (STO) are highly desirable for future generation ULSI applications. Over the past three decades, development of crystalline oxides on silicon has been a great technological challenge as an amorphous silicon oxide layer forms readily on the Si surface when exposed to oxygen preventing the intended oxide heteroepitaxy on Si substrate. Recently, we have successfully grown epitaxial STO thin films on Si(001) surface by using molecular beam epitaxy (MBE) method. Properties of the STO films on Si have been characterized using a variety of techniques including in-situ reflection high energy electron diffraction (RHEED), ex-situ X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The STO films grown on Si(001) substrate show bright and streaky RHEED patterns indicating coherent two-dimensional epitaxial oxide film growth with its unit cell rotated 450 with respect to the underlying Si unit cell. RHEED and XRD data confirm the single crystalline nature and (001) orientation of the STO films. An X-ray pole figure indicates the in-plane orientation relationship as STO[100]//Si[110] and STO(001)// Si(001). The STO surface is atomically smooth with AFM rms roughness of 1.2 AÅ. The leakage current density is measured to be in the low 10−9 A/cm2 range at 1 V, after a brief post-growth anneal in O2. An interface state density Dit = 4.6 × 1011 eV−1 cm−2 is inferred from the high-frequency and quasi-static C-V characteristics. The effective oxide thickness for a 200 Å STO film is around 30 Å and is not sensitive to post-growth anneal in O2 at 500-700°C. These STO films are also robust against forming gas anneal. Finally, STO MOSFET structures have been fabricated and tested. An extrinsic carrier mobility value of 66 cm2 V−11 s−1 is obtained for an STO PMOS device with a 2 μm effective gate length.

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Gas‐source molecular‐beam epitaxy using Si2H6and GeH4and x‐ray characterization of Si1−xGex(0≤x≤0.33) alloys

Journal of Applied Physics ◽

10.1063/1.350639 ◽

1992 ◽

Vol 71 (10) ◽

pp. 4916-4919 ◽

Cited By ~ 7

Author(s):

S. H. Li ◽

S. W. Chung ◽

J. K. Rhee ◽

P. K. Bhattacharya

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

X Ray ◽

Gas Source

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Room-Temperature Wafer Bonded Multi-Junction Solar Cell Grown by Solid State Molecular Beam Epitaxy

MRS Advances ◽

10.1557/adv.2016.429 ◽

2016 ◽

Vol 1 (43) ◽

pp. 2907-2916 ◽

Cited By ~ 3

Author(s):

Shulong Lu ◽

Shiro Uchida

Keyword(s):

Solar Cell ◽

Molecular Beam Epitaxy ◽

Wafer Bonding ◽

Room Temperature ◽

Molecular Beam ◽

Short Circuit ◽

Short Circuit Current ◽

Short Circuit Current Density ◽

Device Structure ◽

Junction Solar Cell

ABSTRACTWe studied the InGaP/GaAs//InGaAsP/InGaAs four-junction solar cells grown by molecular beam epitaxy (MBE), which were fabricated by the novel wafer bonding. In order to reach a higher conversion efficiency at highly concentrated illumination, heat generation should be minimized. We have improved the device structure to reduce the thermal and electrical resistances. Especially, the bond resistance was reduced to be the lowest value of 2.5 × 10-5 Ohm cm2 ever reported for a GaAs/InP wafer bond, which was obtained by the specific combination of p+-GaAs/n-InP bonding and by using room-temperature wafer bonding. Furthermore, in order to increase the short circuit current density (Jsc) of 4-junction solar cell, we have developed the quality of InGaAsP material by increasing the growth temperature from 490 °C to 510 °C, which leads to a current matching. In a result, an efficiency of 42 % at 230 suns of the four-junction solar cell fabricated by room-temperature wafer bonding was achieved.

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