GaAs wires

Figure 13.11. High-frequency behavior of TFTs built with semiconductor wires and ribbons, (a) xs-Si MOSFETs on PI substrates. (Reprinted with permission from Ref. 17. Copyright 2006 IEEE) (b) xs-GaAs MESFETs on PET substrates, (c) Dependence of fT on gate length of xs-GaAs MESFETs. The different symbols represent measurements on different devices the dashed line corresponds to calculation. (Reprinted with permission from Ref. 82. Copyright 2006 American Institute of Physics.)...

Figure 13.12. Images and electrical measurements of integrated circuits that use semiconductor wires and ribbons on plastic, (a) Silicon ribbon five-stage ring oscillator and (b) differential amplifier. (Reprinted with permission from Ref. 87. Copyright 2007 American Institute of Physics.) (c) GaAs logic gates. (Reprinted with permission from Ref. 86. Copyright 2006 Wiley-VCH Verlag.)...

FIGURE 11.6 The increase of conductance with gate voltage along a quantum wire connecting two GaAs/AlGaAs interfaces in a transistor. 

The two parallel ID wires are fabricated by cleaved-edge overgrowth (CEO), see Fig. 1. Initially, a GaAs/AlGaAs heterostructure with two closely situated parallel quantum wells is grown. The upper quantum well is 20 nm wide, the lower one is 30 nm wide and they are separated by a 6 nm AlGaAs barrier... 

Fig. 2. Measurement of G(V, B) for a 2 pm junction. Light shows positive and dark negative differential conductance. A smoothed background has been subtracted to emphasize the spectral peaks and the finite-size oscillations. The solid black lines are the expected dispersions of noninteracting electrons at the same electron densities as the lowest ID bands of the wires, ui) and li). The white lines are generated in a similar way but after rescaling the GaAs band-structure mass, and correspondingly the low-voltage slopes, by a factor of 0.7. Only the fines labeled by a, b, c, and d in the plot are found to trace out the visible peaks in G(V,B), with the fine d following the measured peak only at V > —10 mV.

Arakawa, T., Watabe, H., Nagamune, Y., and Arakawa, Y., Fabrication and microscopic photoluminescence imaging of ridge-type InGaAs quantum wires grown on a (110) cleaved plane of AlGaAs/GaAs superlattice. Appl. Phys. Lett. 69,1294 (1996). 

Based on this, Spirkoska et al. [18] were able to use Raman spectroscopy to distinguish between individual GaAs NWs with majority zinc blende or majority wurtzite structures. Figure 17.4 shows the Raman spectra from three different GaAs NWs with different wurtzite contents. Spectrum a corresponds to a pure zinc blende wire and as expected for a [111] growth direction, only the TO peak is observed. 

The equipment and the experimental procedures using the C02-methanol medium have already been described in previous papers. . For the photoelectrochemical experiments, a stainless steel pressure vessel was equipped with a 2-cm thick quartz window for illumination, p-type InP and GaAs wafers were cut into ca. 0.4 cm x 0.5 cm electrodes and were mounted using epoxy resin. Ohmic contact was made with successive vapor deposition of Zn (30 mn) and Au (100 nm), which was annealed afterward at 425 C in Ar. A silver wire (0.8 mm dia) was used as a quasi-reference electrode (Ag-QRE, ca. +80 mV vs. SCE). A Pt wire (0.8 mm dia) was used as the counter electrode. The photocathode was etched in hot aqua regia for ca. 5 s before each experiment. The electrolyte solution [3 cm, 0.3 mol dm" tetrabutylammonium perchlorate (TBAP) in CH3OH] was placed in a glass cell liner in the stainless steel vessel. Gases were introduced into the pressure vessel and were left to equilibrate for one hour at the desired pressure (1 to 40 atm). 

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