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VOLUME 60 (1994) | ISSUE 12 |
PAGE 849
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Tunneling in a quantizing magnetic field and many-particle features in the tunneling spectra of Schottky-barrier junctions
Kotel'nikov I. N., Shul'man A. Ya., Maude D. K., Portal J.-C.
![The differential tunneling resistance <i>R </i>and the tunneling spectra <i>Rd<sup>2</sup>I/dV<sup>2</sup> </i>of <i>n-</i>GaAs/Au junctions have been studied as a fun ction of the magnetic field <i>В </i>in longitudinal <i>(B\\l) </i>and transverse <i>(B1I) </i>fields up to 23 Τ at 4.2 K. A quantizing magnetic field alters the various <i>R(V) </i>curves in a similar way. It leaves the tunneling spectra essentially unchanged, except at bias voltages <i>V </i>at which there are manifestations of many-particle effects in the tunneling: an anomaly at a zero voltage and phonon features in the tunneling spectra. These results suggest that the behavior of Я as a function of <i>V </i>and <i>В </i>can be described by the multiplicative expression <i>R*-f(V)g(B) </i>within contributions of many-particle interactions (an exchange-correlation interaction and a polaron interaction). Expressions are derived for the behavior <i>R(B) </i>at V=0. Theoretical curves are compared with experimental data. The discrepancies found indicate that it is necessary to consider the change caused in the shape of the self-consistent Schottky barrier by the effect of the quantizing magnetic field on screening. In the case of a longitudinal field, the only possible cause of a magnetoresistance of tunnel junctions would be Landau quantization of the spectrum of free carriers. A comparison of the <i>R </i>curves with Shubnikov-de Haas oscillations of the bulk resistivity of n-GaAs indicates that scattering processes which suppress magnetic quantization in the interior of the semiconductor, when the condition <b><i>w<sub>c</sub>t</i></b><i>^1 </i>does not hold, do not prevent quantization of electrons near the Schottky barrier in far weaker fields.](/ps/1359/article_20541_800_head.png)
The differential tunneling resistance R and the tunneling spectra Rd2I/dV2 of n-GaAs/Au junctions have been studied as a fun ction of the magnetic field В in longitudinal (B\\l) and transverse (B1I) fields up to 23 Τ at 4.2 K. A quantizing magnetic field alters the various R(V) curves in a similar way. It leaves the tunneling spectra essentially unchanged, except at bias voltages V at which there are manifestations of many-particle effects in the tunneling: an anomaly at a zero voltage and phonon features in the tunneling spectra. These results suggest that the behavior of Я as a function of V and В can be described by the multiplicative expression R*-f(V)g(B) within contributions of many-particle interactions (an exchange-correlation interaction and a polaron interaction). Expressions are derived for the behavior R(B) at V=0. Theoretical curves are compared with experimental data. The discrepancies found indicate that it is necessary to consider the change caused in the shape of the self-consistent Schottky barrier by the effect of the quantizing magnetic field on screening. In the case of a longitudinal field, the only possible cause of a magnetoresistance of tunnel junctions would be Landau quantization of the spectrum of free carriers. A comparison of the R curves with Shubnikov-de Haas oscillations of the bulk resistivity of n-GaAs indicates that scattering processes which suppress magnetic quantization in the interior of the semiconductor, when the condition wct^1 does not hold, do not prevent quantization of electrons near the Schottky barrier in far weaker fields.
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