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44
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84927314401
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Bias polarity is with respect to the substrate.
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45
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84927314400
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While the semiclassical geometric capacitance does not describe the problem (Refs. 6, 19, and 20), an ``effective capacitance'' of the well to the outside world can be formally defined as CW= e2/2UNe; thus defined CW depends, for example, on the shape of the confining potential, NW, and B. We estimate CWapprox 3 times 10-17 F for NW=1 (U1eapprox 2.5 meV) for the device of Fig. 3.
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46
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84927314399
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For the larger device of Ref. 6, we determined a approx 120 nm by fitting the size quantization and a approx 130 nm by scaling the peak current density; for the device of Fig. 3, we obtain a approx 50 nm (for NW=1) from the size quantization.
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47
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84927314398
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U2e is the second-electron charging energy, not the two-electron charging energy. That is, the first electron can tunnel into the well when Δ E(1)= E1+ U1e (the kinetic energy of the in-plane motion of the one-electron ground state is E1); the second electron can tunnel into the well when Δ E(2)= (1/2E2- E1+ U2e) + Δ E(1)= 1/2 E2+ U1e+ U2e (the kinetic energy of the two-electron ground state is E2). In the limit UNe<< δ E (for example, ε -> inf ), the ground-state kinetic energies are integer multiples of hbar ω0 (for example, E1= E0,0). If UNeapp δ E, however, Coulomb interaction mixes the single-particle states even for NW=1; that is, the total NW ground-state energy is minimized by an admixture of the higher single-particle states.
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49
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84927314397
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Many contributions in Resonant Tunneling in Semiconductors, edited by L. L. Chang, E. E. Mendez, and C. Tejedor (Plenum, New York, 1991).
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50
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84927314396
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The short-period modulation is superficially similar to the ``universal'' conductance fluctuations, but occurs in tunneling transport. Emitter electrode contains only app nEa3approx 100 donors in the volume from which electrons tunnel. Thus, the density of states in the emitter is modulated on the energy scale of EF/ 100 approx 0.2 meV giving rise to (0.2 meV)/[e α(-)] approx 0.8 mV modulation of the tunneling current. As bias is raised, a greater number of donors (within the energy interval Δ E) contribute to the tunneling current and the influence of individual donors averages out.
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65
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84927314395
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An interesting feature is that a small bump emerges in the tail region of FCS as T increases in the negative bias. It can be clearly seen in the I-V curves at 1.3 and 2.1 K [Figs. 11(b) and 12]. We believe that this bump has the same origin as the short-period modulation (Ref. 34).
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66
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2642520121
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In a similar experimental setup, electron temperatures as low as 15 mK were achieved in the fractional quantum Hall effect regime [, ]. Thus we expect to achieve comparable electron temperatures in present samples.
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(1990)
Phys. Rev. Lett.
, vol.65
, pp. 907
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Goldman, V.J.1
Jain, J.K.2
Shayegan, M.3
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