Resistivity of Dilute 2D Electrons in an Undoped GaAs Heterostructure

Lilly, Michael; Reno, John L.; Simmons, J. A.; Spielman, I. B.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.; Hwang, E. H.; Sarma, S. Das

doi:10.1103/physrevlett.90.056806

Cited by 119 publications

(136 citation statements)

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“…In other words the 2DHG shows 'metallic' behaviour at low T. Such nonmonotonic behaviour has been observed earlier in n-and p-GaAs heterojunctions and QWs [11][12][13]. It is found that T 0 depends approximately linearly on p (see figure 4).…”

supporting

confidence: 74%

Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

Taneja

Shlimak

Narayan

et al. 2017

J. Phys.: Condens. Matter

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Ambipolar transport, or the ability to switch between electrons and holes in the same device, has strong implications towards the implementation of functional devices: for instance, creating gate-defined n-and p-type conducting channels in the same device can be exploited in thermoelectric power generation, as well as towards spintronic applications by tuning between large (holes) and small (electrons) spinorbit coupling. Equally, ambipolar transport is also of much interest in fundamental studies of scattering, interaction and spin related phenomena since electrons and holes have very different effective masses, band structures and spin properties [1,2]. Chen et al [1] and Croxall et al [2] studied the density dependence of µ p and µ e in ambipolar GaAs/AlGaAs single heterojunction devices and quantum wells (QWs) respectively. The mobilities were found to depend not only on the AbstractWe report the results of an investigation of ambipolar transport in a quantum well of 15 nm width in an undoped GaAs/AlGaAs structure, which was populated either by electrons or holes using positive or negative gate voltage V tg , respectively. More attention was focussed on the low concentration of electrons n and holes p near the metal-insulator transition (MIT). It is shown that the electron mobility µ e increases almost linearly with increase of n and is independent of temperature T in the interval 0.3 K-1.4 K, while the hole mobility µ p depends non-monotonically on p and T. This difference is explained on the basis of the different effective masses of electrons and holes in GaAs. Intriguingly, we observe that at low p the source-drain current (I SD )-voltage (V) characteristics, which become non-linear beyond a certain I SD , exhibit a re-entrant linear regime at even higher I SD . We find, remarkably, that the departure and reappearance of linear behaviour are not due to non-linear response of the system, but due to an intrinsic mechanism by which there is a reduction in the net number of mobile carriers. This effect is interpreted as evidence of inhomogeneity of the conductive 2D layer in the vicinity of MIT and trapping of holes in 'dead ends' of insulating islands. Our results provide insights into transport mechanisms as well as the spatial structure of the 2D conducting medium near the 2D MIT.Keywords: non-linear I-V characteristics, two-dimensional hole gas, metal-insulator transition (Some figures may appear in colour only in the online journal)Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.1361-648X/17/185302+7$33.00

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supporting

confidence: 74%

Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

Taneja

Shlimak

Narayan

et al. 2017

J. Phys.: Condens. Matter

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“…In particular, the proximity of ionized dopant impurities (modulation or δ-doping, or even a doped cap) significantly lowers mobility at low carrier densities, as well as contributes to Random Telegraph Signal noise. Overcoming mobility degradation in bulk 2D studies is possible by offsetting the dopants from the heterointerface by an extremely thick spacer layer 6 , but an offset of more than 100 − 200nm becomes untenable when defining certain features of mesoscopic structures, such as narrow quantum point contacts (∼ 500nm) or quantum dots (∼ 50nm). The alternative method of doping a quantum well from underneath only, creating an inverted 2D gas, carries the cost of interface roughness scattering from inverted interfaces, and does not yield the best mobilities.…”

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confidence: 99%

Low temperature transport in undoped mesoscopic structures

Sarkozy

Gupta

Siegert

et al. 2009

Applied Physics Letters

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Using high quality undoped GaAs/AlGaAs heterostructures with optically patterned insulation between two layers of gates, it is possible to investigate very low density mesoscopic regions where the number of impurities is well quantified. Signature appearances of the scattering length scale arise in confined two dimensional regions, where the zero-bias anomaly (ZBA) is also observed. These results explicitly outline the molecular beam epitaxy growth parameters necessary to obtain ultra low density large two dimensional regions as well as clean reproducible mesoscopic devices. PACS numbers:With potential applications to quantum computation as well as innate interest in fundamental physics such as localization and Quantum Hall effects, significant resources have been devoted to the study of electronelectron interactions 1,2 . Regardless of dimensionality, the relative importance of interactions increases with decreasing carrier concentration, providing substantial impetus for the study of low density systems. It is instructive to quantitatively analyze the requirements to ensure that phenomena observed are intrinsic to interactions in the two dimensional electron/hole gas (2DEG/2DHG), and not merely manifestations of impurity effects or disorder based localization. The cleanliness of the 2D gas at low densities is also crucial in studying pinch-off regions in one-dimensional (1D) channels and very low conductance characterization of zero-dimensional (0D) quantum dots, although this point is not often emphasized.

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“…The electronic contribution to the resistance behaves nonmonotonically, first increasing and then decreasing as T is lowered past a characteristic temperature T 0 , which is comparable to T F . This feature, better observed in low density 2D systems, occurs when carriers become semi-degenerate and has been observed in the three most commonly studied 2D systems: p-GaAs [19][20][21][22], n-Si [23,24] and n-GaAs [25,26]. The mechanism of this non-monotonic R xx (T) has been a key point in several leading theories of the 2D metallic transport [7,8,[27][28][29] and is the subject of this experimental study.…”

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Impact of short-range scattering on the metallic transport of strongly correlated two-dimensional holes in GaAs quantum wells

et al. 2014

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Understanding the non-monotonic behavior in the temperature dependent resistance, R(T), of strongly correlated two-dimensional (2D) carriers in clean semiconductors has been a central issue in the studies of 2D metallic states and metal-insulator-transitions. We have studied the transport of high mobility 2D holes in 20nm wide GaAs quantum wells (QWs) with varying short-range disorder strength by changing the Al fraction x in the Al x Ga 1-x As barrier. Via varying the short range interface roughness and alloy scattering, it is observed that increasing x suppresses both the strength and characteristic temperature scale of the 2D metallicity, pointing to the distinct role of short-range versus long-range disorder in the 2D metallic transport in this correlated 2D hole system with interaction parameter r s~ 20.PACS Numbers: 71.30.+h, 73.63.Hs For the past thirty years, two-dimensional (2D) quantum systems have been a rich area of concentrated study for both theorists and experimentalists to explore the interplay between Coulomb interaction and disorder effects [1][2][3][4]. In the case of 2D electrons with ultra-low density and weak disorder, the quantum and strongly interacting nature of the systems becomes so prominent that various complex quantum phases and phase transitions may exist according to theory [5][6][7][8][9][10][11]. Obtaining a clear understanding of such strongly correlated 2D systems thus remains to be extremely important in the field of many-body physics.In 2D electron or hole samples with high mobility, an intriguing metal to insulator transition (MIT) was observed in zero magnetic field (B=0) with the carrier density as the tuning parameter [2,3,12]. Although strong electron-electron interactions are believed to be an essential factor in the origin of this MIT in 2D, the effects of disorder seem to be non-negligible and must be incorporated in order to reconcile the subtle differences in all the 2D MIT experiments over a range of disorder and interaction strength [2,3,[13][14][15]. While the understanding of the 2D MIT in the critical regime continues to advance [13][14][15][16][17], the mechanism of the 2D metallic conduction in the metallic regime (resistivity <

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Resistivity of Dilute 2D Electrons in an Undoped GaAs Heterostructure

Cited by 119 publications

References 16 publications

Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

Low temperature transport in undoped mesoscopic structures

Impact of short-range scattering on the metallic transport of strongly correlated two-dimensional holes in GaAs quantum wells

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