We have investigated in detail the influence of interlayer structures on nonalloyed ohmic contact resistance (ρc), in terms of the crystalline defects and the potential barrier at the interlayer/GaAs interface. The interlayer structures are a graded-band-gap InAs/GaAs strained-layer superlattice (graded SLS), a graded-band-gap InGaAs, and conventional SLSs without graded band gaps. A two-layer transmission line model indicates that the barrier resistance in the interlayer highly depends on the interlayer structure: ≤5×10−8 Ω cm2 for the graded SLS and graded InGaAs interlayers and 10−5–10−6 Ω cm2 for the conventional SLS interlayers. To explain the large dependence of the interlayer structure, first, the density and distribution of the misfit dislocations and stacking faults caused by the large lattice mismatch between InAs and GaAs have been investigated in detail by high-resolution transmission electron microscopy. In the graded SLS and conventional SLS interlayers, the influence of the high-density depletion regions spread near the crystalline defects is found to be negligible because of the high doping concentrations (∼1019 cm−3) in the interlayers. Second, the potential barrier at the interlayer/GaAs interface has been investigated by simulating the barrier resistance. The potential barrier profile is calculated self-consistently with Poisson’s equation and the Schrödinger equation. Tunneling current through the barrier is analyzed using the Wentzel–Kramers–Brillouin approximation or the numerical wave solution to the Schrödinger equation. The graded SLS interlayer has the effectively smooth conduction band profile without the barriers, which is similar to that of the graded InGaAs interlayer, because of its short period SLS. In the conventional SLS interlayers, the reasonable barrier heights of 0.14–0.26 eV obtained by this simulation indicates that these barriers are the dominant factor which increases the contact resistances. For the low-resistance nonalloyed ohmic contact, therefore, a smooth conduction band profile without band discontinuity is more predominant than the reduction in the crystalline defect density.
State selected ion-molecule reactions by a TESICO technique. IV. Relative importance of the two spinorbit states of Ar+ in the charge transfer reactions with N2 and COIn an ion beam study of the luminescent charge-transfer reaction p+ e Po 1 2) CO(X l~+been examined at a collision energy of 11.9 eV CM' using high (~I A FWHM) optical resolution. For the near-resonant vibrational level v' = 5, the 2II3/2 S/O component of CO+ (A) was found to be formed with an excess population of ~40% relative to the 2IIl/2 component. Lower-resolution data show a similar enhancement of 2II3/2 also for the v' =6 level, but not for v' =4 and 3. This can be rationalized in terms of recent ab initio calculations. Also in accordance with these calculations, the product rotational excitation was found to be very low in the v' = 5 level. The best-fit rotational "temperature" is for this level actually less than the target gas temperature, a common artifact in collisional processes with small angular momentum transfer.
The interaction of O(1 D 2) with HCl: The initial vibrational distributions in the OH(2Π) produced by chemical reaction, and the HCl(1Σ+) produced by E-V energy transfer J. Chem. Phys. 88, 985 (1988); 10.1063/1.454124 Product state distribution in the reaction O(1 D 2)+HCl→OH+Cl J. Chem. Phys. 73, 5393 (1980); 10.1063/1.439934Vibrational product state distributions of ion-molecule reactions by infrared chemiluminescence: Cl−+HBr,HI→HCl(v)+Br−,I− The chemiluminescent charge transfer reaction of 0 + eD)ions with HCl has been studied in the energy range of7 to 100 eV e . m .• The vibrational population distributions of the HCl + (A 2l; + ,v') product have been analyzed from the emission spectra of the A ..... X transition. At low collision energy the distribution has a peak at v' = 3. The partial reaction cross section 0'( 3) for this level increases with decreasing collision energy. The features of the reaction are very similar to the F + + CO ..... F + CO + (A) reaction reported previously. The mechanism has been discussed on the basis of curve crossing between the initial and final states along the HCl vibrational coordinate in the asymptotic region ofthe [O-HCl] + system. The projectile ions C + and N + have also been tested for the charge transfer reaction of HCl(X) ..... HCl+(A).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.