-
[show abstract]
[hide abstract]
ABSTRACT: We report transport properties of two single-electron transistors (SETs) on a Ga N / Al Ga N heterostructure. The first SET formed accidentally in a quantum point contact near pinchoff. Its small size produces large energy scales (a charging energy of 7.5 meV and well-resolved excited states). The second, intentionally fabricated SET is much larger. More than 100 uniformly spaced Coulomb oscillations yield a charging energy of 0.85 meV . Excited states are not resolvable in Coulomb diamonds, and Coulomb blockade peak height remains constant with increasing temperature, indicating that transport is through multiple quantum levels even at the 450 mK base electron temperature of our measurements. Coulomb oscillations of both SETs are highly stable, comparable to the best GaAs SETs.
Applied Physics Letters 08/2006; · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: High mobility two-dimensional electron systems in GaN/AlGaN heterostructures have been realized by plasma assisted molecular beam epitaxy on GaN templates. In the density range of 1011 cm–2 to 1012 cm–2, mobility values exceeding 160000 cm2/Vs have been achieved. Scattering mechanisms that presently limit the production of higher mobility samples are discussed. We present results of a systematic study of the weak localization and antilocalization corrections to the classical conductivity at very low magnetic fields. The unambiguous observation of a conductivity maximum at B = 0 suggests that spin–orbit scattering is not negligible in GaN heterostructures as one might expect for a wide-bandgap system. We have recently realized electron transport through GaN nanostructures. We report on the transport properties of the first quantum point contacts (QPCs) in GaN. These devices are used to study one-dimensional transport in the Nitride system. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
physica status solidi (b) 05/2006; 243(7):1706 - 1712. · 1.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We study the transport properties of quantum point contacts in a GaN/AlGaN heterostructure. The conductance of our devices shows well-quantized plateaus, which spin-split in high perpendicular magnetic field. The g factor is 2.55, as derived from the point contact subband splitting versus perpendicular magnetic field. In addition to the well-resolved plateaus, we also observe evidence of “0.7 structure” which has been mainly investigated in the GaAs system.
Applied Physics Letters 02/2005; 86(7):073108-073108-3. · 3.84 Impact Factor
