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- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Comparison of optical and structural quality of GaIn(N) As analog and digital quantum wells grown by molecular beam epitaxy
- 2008
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Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 23:12, s. 125002-
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Tidskriftsartikel (refereegranskat)abstract
- A set of Ga0.625In0.375(N) As single quantum well (QW) samples with the identical total amounts of Ga and In and QW thicknesses was designed and grown by both the analog and the digital methods using molecular beam epitaxy. The N exposure time in the GaInNAs samples was kept the same. The inter-band gap recombination in the analog and the digital InGaAs QWs appears in a similar transition energy range as a result of In segregation. Temperature-dependent photoluminescence (PL) measurements were performed on the GaInNAs samples. An S-shaped dependence of the transition energy on temperature was observed in the digital GaInNAs QWs but not in the analog GaInNAs QW. Post-growth rapid thermal annealing had remarkably different effects on the PL intensity: an increase for the analog InGaAs QW and for the analog and digital GaInNAs QWs, but a decrease for the digital InGaAs QW with increasing annealing temperature. The GaIn(N) As samples grown by the digital method showed weaker PL intensities and smaller wavelength blue-shifts than the similar samples grown by the analog method. Possible strain relaxation mechanisms are discussed.
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| 2. |
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| 3. |
- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Effect of bismuth on structural and electrical properties of InAs films grown on GaAs substrates by MBE
- 2015
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 425, s. 89-93
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Tidskriftsartikel (refereegranskat)abstract
- © 2015 Elsevier B.V. All rights reserved. InAs films were grown on GaAs substrates by molecular beam epitaxy (MBE) without or with different Bi fluxes. The effect of Bi on the structural and electrical properties of the InAs films was studied. Atomic Force Microscopy (AFM) measurement showed clear surface steps in all samples, indicating an over-flow growth mode. A more uniform distribution and narrower spacing of the surface steps were observed with increased Bi fluxes. Small area AFM scans showed reduced surface roughness with increased Bi fluxes. Whereas from large area scans, reduced surface roughness was only observed in samples grown under low Bi fluxes, and a deteriorated surface was obtained in the sample grown under the highest Bi flux. Bi was not compositionally incorporated to the InAs films confirmed by X-ray diffraction (XRD) and Second Ion Mass Spectroscopy (SIMS) measurements. The electron mobility of the InAs films, measured at room temperature, decreased monotonically with increased Bi fluxes. This is correlated to the Transmission Electron Microscopy (TEM) results in which increased threading dislocation (TD) densities were shown with increased Bi fluxes. Therefore, Bi-mediated growth deteriorates the electron mobility of the MBE-grown InAs films, whereas smoother surface can be obtained by applying low Bi fluxes. Possible mechanisms were proposed to explain these phenomena.
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| 4. |
- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Effect of buffer design on structural and electrical properties of InAs films grown on GaAs substrates
- 2014
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Ingår i: the 41st international symposium on compound semiconductors, Montepillier, France.
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Konferensbidrag (refereegranskat)abstract
- Different buffer structures were grown by molecular beam epitaxy (MBE) to accommodate the large lattice mismatch of InAs with GaAs substrate. A novel graded digital superlattice (GDSL) buffer design was proposed and compared with the common one-step buffer and linear alloy graded (LAG) buffer designs. Effect of buffer structures on structural and electrical properties of the InAs films was investigated. High quality InAs films were obtained on GaAs substrates.
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| 5. |
- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Effect of Buffer Quality on the Performance of InAs/AlSb Heterostructure Backward Tunneling Diode
- 2014
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035.
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Konferensbidrag (refereegranskat)abstract
- InAs/AlSb Heterostructure Backward Tunneling Diodes (HBTDs) were grown on semi-insulating GaAs (100) substrate using molecular beam epitaxy (MBE). The current-voltage characteristics of the InAs/AlSb HBTDs, both at room temperatures (RT) and cryogenic temperatures, have been studied as a function of the InAs buffer thickness. It has been found that a thicker InAs buffer doesn’t improve the surface roughness but decreases the threading dislocation (TD) density, thus a higher curvature coefficient in the current-voltage characteristics near zero-bias is obtained.
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