Room temperature polarized photoreflectance characterization of GaAlAs/InGaAs/GaAs high electron mobility transistor structures including the influence of strain relaxation

Abstract

Articles you may be interested inGrowth parameter optimization and interface treatment for enhanced electron mobility in heavily strained GaInAs/AlInAs high electron mobility transistor structures J. Appl. Phys. 115, 043718 (2014); 10.1063/1.4863332Mobility enhancement by reduced remote impurity scattering in a pseudomorphic In 0.7 Ga 0.3 As/In 0.52 Al 0.48 As quantum well high electron mobility transistor structure with (411)A super-flat interfaces grown by molecularbeam epitaxy Room-temperature photoreflectance and photoluminescence characterization of the AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures with varied quantum well compositional profiles Using room temperature photoreflectance ͑PR͒ we have characterized the properties of three GaAlAs/InGaAs/GaAs high electron mobility transistor structures with two different well widths fabricated by molecular beam epitaxy on ͑001͒ GaAs substrates. The samples were denoted as #1, #2, and #3 with well widths of 140, 160, and 160 Å, respectively. Samples #2 and #3 were grown on substrates with different threading dislocation densities. For the latter two samples the well width exceeds the pseudomorphic limit so that there are some strain relaxation and related misfit dislocations as determined from the x-ray measurements. In order to detect the anisotropic strain of the misfit dislocations related to strain relaxation, the PR measurements were performed for incident light polarized along ͓110͔ and ͓11 0͔ directions. Evidence for the influence of the strain relaxation upon the relaxed channel was provided by the observed anisotropy of the polarized PR signal in the InGaAs channel layer. Signals have been observed from every region of the sample, making it possible to evaluate the In and Al compositions, channel width and two-dimensional electron gas density, as well as the properties of the GaAs/GaAlAs multiple quantum well buffer layer.

Spin-dependent electronic structure of the Co/Al(OP)3interface

“…The two states are named HIS1 and HIS2, respectively. In analogy with the HOMO of Al(OP) 3 , the energetic position of the two interface states shifts to lower energy with increasing coverage of Al(OP) 3 , which we interpret again as a result of the interaction of these states with the surrounding potential of Co, the neighboring molecules and the vacuum [21].…”

“…In contrast to the work function, the HOMO position does not remain constant for coverage above 1.5 nm. The shift in energy of the HOMO position is most probably due to the different conditions experienced by the Al(OP) 3 molecules in a submonolayer, a monolayer, a bulk molecular film and at the surface of a molecular film, as described by Hill et al [21]. In particular, the surrounding potential of the cobalt film of the neighboring molecules and of the vacuum will vary with coverage.…”