We have studied the evolution of AlSb-on-InAs͑001͒ surfaces and interfaces grown by molecular-beam epitaxy using in situ scanning tunneling microscopy. We find that forming InSb-like interfacial bonds on an InAs͑001͒-͑2ϫ4͒ surface creates surface roughness because the surface In coverage inherent to the ͑2ϫ4͒ reconstruction is insufficient to form a complete InSb͑001͒-͑1ϫ3͒-like surface layer. This morphological roughness can be eliminated by depositing additional In to compensate for the different compositions of the reconstructions. We have also grown three different 5-monolayer-thick films of AlSb on the InSb-like interface to study the effect of growth conditions on the film surface morphology. The AlSb surface can be improved by either raising the growth temperature or by growing the film using migration-enhanced epitaxy. Finally, we present electrical characterization of InAs/AlSb/GaSb resonant interband tunneling devices fabricated with different growth procedures. The possible effects of various growth procedures on interfacial quality and device properties are discussed.

Articles you may be interested inMolecular beam epitaxy growth of high electron mobility InAs/AlSb deep quantum well structure J. Appl. Phys. 114, 013704 (2013); 10.1063/1.4811443 Molecular beam epitaxial growth of metamorphic AlInSb/GaInSb high-electron-mobility-transistor structures on GaAs substrates for low power and high frequency applications J. Appl. Phys. 109, 033706 (2011); 10.1063/1.3544041Suppression of surface segregation of silicon dopants during molecular beam epitaxy of ( 411 ) A In 0.75 Ga 0.25 As ∕ In 0.52 Al 0.48 As pseudomorphic high electron mobility transistor structures Study of highly selective wet gate recess process for Al 0.25 Ga 0.75 As/GaAs based pseudomorphic high electron mobility transistors Comparison of As-and P-based metamorphic buffers for high performance InP heterojunction bipolar transistor and high electron mobility transistor applications High electron mobility transistors ͑HEMTs͒ with InAs channels and antimonide barriers were grown by molecular beam epitaxy. Both Si and Te were successfully employed as n-type dopants. Sheet resistances of 90-150 ⍀/ᮀ were routinely achieved on a variety of heterostructures with nonuniformities as low as 1.5% across a 75 mm wafer. X-ray diffraction measurements show that the InAs channels are in tension, coherently strained to the Al͑Ga͒Sb buffer layers. Atomic force microscopy measurements demonstrate that the surfaces are relatively smooth, with rms roughness of 8 -26 Å over a 5ϫ5 m 2 area. These results demonstrate that the growth of InAs HEMTs has progressed to the point that the fabrication of circuits should be feasible.

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NiAuGeAu ohmic contacts for a planar InP-based high electron mobility transistor structure with suppressed drain conductance frequency dispersion

The proton and "C shielding constants in CH, , C,H,, C,H, and some other gaseous hydrocarbons have been studied as functions of density at temperatures in the range 180-370 K. The linear coefficients describing the density dependence of the shielding, after correcting for bulk susceptibility, increase substantially as the temperature is reduced, indicating stronger intermolecular interactions. (Some of the required magnetic susceptibilities were determined in this work by an NMR method). The "C measurements for CH, are close to those of an earlier study; the results for the other gases are new. The linear coefficient is substantially greater for the carbon shielding of the methyl group in propane than for the methylene group at any temperature, but there is virtually no distinction between tbe linear coefficients for the proton shielding in this gas. Values for du,/dT, the temperature dependence of the shielding extrapolated to zero density, are also presented for both proton and "C shielding in the bydrocarboos. They are positive and negative in different instances. It is shown from this and earlier gas-phase studies that standard literature values of the methane "C shielding relative to the ''C shielding in tbe other bydrocarboos are in error.