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Theoretical Investigation on Electron Mobility in AlInGaN/InGaN Heterostructures
摘要： The dependences of electron mobility in AlInGaN/InGaN heterostructure on the barrier and channel alloy compositions and on temperature are investigated including six scattering processes: acoustic deformation potential (DP) scattering, piezoelectric field (PE) scattering, polar optical phonons (PO) scattering, dislocation impurity (DIS) scattering, interface roughness (IRF) scattering, and alloy disorder (ADO) scattering. The results show that ADO scattering is the most important scattering mechanism, and specifically channel alloy disorder gets severer than barrier alloy disorder except for InGaN channels with very low indium content (near 0) or extremely high indium mole fraction (near 1). The variations of the barrier strain, two-dimensional electron gas (2DEG) density, 2DEG mobility, and conductivity in AlInGaN/In0.04Ga0.96N heterostructure with full barrier alloy composition are summarized. The results indicate that relatively large aluminum content and small indium mole fraction are desired for higher conductivity. By comparing the temperature-dependent transport properties of Al0.83In0.13Ga0.04N/InGaN heterostructures with different InGaN compositions, we find that it is the ADO scattering and PO scattering that determine 2DEG mobility change and the mobility exhibits a weaker dependence on temperature with increasing indium mole fraction in InGaN channel.
关键词： scattering mechanisms,mobility,temperature,two-dimensional electron gas
更新于2025-09-23 15:23:52
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Unusual Electric and Optical Tuning of KTaO <sub/>3</sub> -Based Two-Dimensional Electron Gases with 5d Orbitals
摘要： Controlling electronic processes in low dimension electron system is centrally important for both fundamental and applied researches. While most of the previous works focused on SrTiO3-based two-dimensional electron gases (2DEGs), here we report on a comprehensive investigation in this regard for amorphous-LaAlO3/KTaO3 2DEGs with the Fermi energy ranging from ~13 meV to ~488 meV. The most important observation is the dramatic variation of the Rashba spin-orbit coupling (SOC) as Fermi energy sweeps through 313 meV: The SOC effective field first jumps and then drops, leading to a cusp of ~2.6 T. Above 313 meV, an additional species of mobile electrons emerges, with a 50-fold enhanced Hall mobility. A relationship between spin relaxation distance and the degree of band filling has been established in a wide range. It indicates that the maximal spin precession length is ~70.1 nm and the maximal Rashba spin splitting energy is ~30 meV. Both values are much larger than the previously reported ones. As evidenced by density functional theory calculation, these unusual phenomena are closely related to the distinct band structure of the 2DEGs composed of 5d electrons. The present work further deepens our understanding of perovskite conducting interfaces, particularly those composed of 5d transition metal oxides.
关键词： oxide interfaces,spin-orbital coupling,two-dimensional electron gas,optical gating,gating effect
更新于2025-09-23 15:22:29
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Electric-Field Control of Dirac Two-Dimensional Electron Gas in PbTe/CdTe Heterostructures
摘要： Two-dimensional electron gases (2DEGs) confined to quantum wells trigger rich emergent phenomena and serve as a host for high-speed electronics. 2DEG in PbTe/CdTe heterostructure was predicted to be Dirac electrons and confirmed by recent experiments. Here, we demonstrate the manipulation of electrical transport properties of this 2DEG with extremely high mobility and unique electron structure by ionic liquid-gating. The extreme capacitance of carrier modulation enables to tune the band structure. With a change of the gate voltage, the Fermi level moves to the conduction band and crosses the Dirac Point, leading to the shift of quantum oscillation. Our results may offer new insight toward electronic application with on-demand properties.
关键词： Fermi surface,molecular beam epitaxy,ionic liquid gating,quantum oscillation,two-dimensional electron gas
更新于2025-09-23 15:22:29
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Highly conductive two-dimensional electron gas at the interface of Al2O3/SrTiO3
摘要： We create a two-dimensional electron gas at the Al2O3/SrTiO3/LaAlO3 heterostructures using pulsed laser deposition, which exhibits a decreasing sheet resistance with increasing growth temperatures of Al2O3 films. Structural characterizations of films are confirmed by cross-sectional transmission electron microscopy. Compared with these heterostructures with Al2O3 films deposited on pristine SrTiO3 and TiO2-terminated SrTiO3 substrates, the Al2O3/SrTiO3/LaAlO3 heterostructures are more conductive. X-ray photoelectron spectroscopy indicates the formation of oxygen vacancies at the SrTiO3 side of the interface, which results from the redox reactions by reducing SrTiO3 films. Furthermore, the existence of oxygen vacancies on the SrTiO3 side is verified by a blue-light emission.
关键词： Al2O3/SrTiO3/LaAlO3 heterostructures,pulsed laser deposition,oxygen vacancies,two-dimensional electron gas,conductivity
更新于2025-09-23 15:21:21
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Ultrahigh-Speed Mid-Infrared Photodetectors With 2-D Electron Gas in a CdTe/PbTe Heterojunction
摘要： A CdTe/PbTe heterojunction (HJ) yields two-dimensional electron gas (2DEG) with a high electron density and mobility. Ultrahigh-speed and room-temperature operating mid-infrared photodetectors are developed with the 2DEG. The photoresponse of the detectors originates from the intrinsic response of PbTe by virtue of the conduction-band and valence-band alignment of the HJ. The extremely short rise and decay photoresponse time demonstrate a major advantage of the 2DEG. At λ = 3.0 μm and a bias voltage of 100 mV, the responsivity and detectivity reach 0.94 A/W and 2 × 1010 Jones, respectively. The excellent performance of the detectors renders promising applications in novel mid-infrared frequency detection systems.
关键词： two-dimensional electron gas (2DEG),room-temperature (RT) operation,ultrahigh-speed response,Detectivity,mid-infrared detector
更新于2025-09-23 15:21:01
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Effect of illumination on quantum lifetime in GaAs quantum wells
摘要： Low-temperature illumination of a two-dimensional electron gas in GaAs quantum wells is known to greatly improve the quality of high-field magnetotransport. The improvement is known to occur even when the carrier density and mobility remain unchanged, but what exactly causes it remains unclear. Here, we investigate the effect of illumination on microwave photoresistance in low magnetic fields. We find that the amplitude of microwave-induced resistance oscillations grows dramatically after illumination. Dingle analysis reveals that this growth reflects a substantial increase in the single-particle (quantum) lifetime, which likely originates from the light-induced redistribution of charge enhancing the screening capability of the doping layers.
关键词： quantum lifetime,microwave photoresistance,GaAs quantum wells,illumination effect,two-dimensional electron gas
更新于2025-09-23 15:21:01
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Polarization induced two-dimensional electron gas in ZnO/ZnMgO Heterointerface for High-performance enhanced UV photodetector
摘要： The spontaneous formation of two-dimensional electron gas (2DEG) with a high carrier density (~1018 cm-3) was achieved at a ZnO/Mg0.2Zn0.8O interface grown using a facile radio-frequency magnetron sputtering system on a quartz substrate. Compared with Mg0.2Zn0.8O ultraviolet (UV) photodetectors (PDs) with and without a ZnO buffer layer, the PD based on ZnO/Mg0.2Zn0.8O bilayer films exhibited not only sensitivity to dual wavelength in the UV region, but also significantly enhanced spectral responsivity, photocurrent-to-dark current ratio (107), specific detectivity (1014), and UV/visible rejection ratio of about four orders of magnitude at a low operating voltage bias. Induced by 2DEG, the external quantum efficiency (EQE) of photodetector reached 14858% at 10 V, indicating that a considered high gain was achieved in the device based on this heterojunction architecture. The gain mechanism was further demonstrated by polarization induction and band bending in detail. This application of 2DEG in a practical detector offers a novel and effective approach for the substantial improvement in the high-performance of ZnO/Mg0.2Zn0.8O dual-band UV PDs.
关键词： two-dimensional electron gas,polarization,high-performance UV PDs,ZnO/Mg0.2Zn0.8O heterointerface,gain
更新于2025-09-12 10:27:22
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Review of photoresponsive properties at SrTiO <sub/>3</sub> -based heterointerfaces
摘要： The two-dimensional electron gas at SrTiO3-based heterointerfaces has received a great deal of attention in recent years owing to their potential for the exploration of emergent physics and the next generation of electronics. One of the most fascinating aspects in this system is that the light, as a powerful external perturbation, can modify its transport properties. Recent studies have reported that SrTiO3-based heterointerfaces exhibit the persistent photoconductivity and can be tuned by the surface and interface engineering. These researches not only reveal the intrinsic physical mechanisms in the photoresponsive process, but also highlight the ability to be used as a tool for novel all-oxide optical devices. This review mainly contraposes the studies of photoresponse at SrTiO3-based heterointerfaces.
关键词： persistent photoconductivity (PPC),complex oxides,two-dimensional electron gas,LaAlO3/SrTiO3 heterointerfaces
更新于2025-09-10 09:29:36
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Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation
摘要： An analytical model is presented to calculate the two-dimensional electron gas (2DEG) density and barrier height of bare surface AlGaN/AlN/InGaN/GaN double heterostructures, which use InGaN as the conducting layer. The basic model is derived from electrostatic analysis of the di?erent material interfaces. The e?ect of strain relaxation in the InGaN layer is also incorporated here. Further, the impact of a two-dimensional hole gas at the InGaN/GaN interface, formed when the InGaN layer thickness is high, has been considered. The presented results are seen to agree with the available experimental results. Thus, this model can be a useful tool in the design and modeling of InGaN-based III-nitride heterostructures.
关键词： two-dimensional hole gas,AlGaN/InGaN/GaN heterostructure,strain relaxation,two-dimensional electron gas
更新于2025-09-09 09:28:46
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/epitaxial graphene van der Waals heterostructure
摘要： We report on direct observation of interface superconductivity in single-unit-cell SnSe2 films grown on graphitized SiC(0001) substrate. The tunneling spectrum in the superconducting state reveals a rather conventional character with a fully gapped order parameter. The occurrence of superconductivity is further confirmed by the observation of vortices under external magnetic field. Through interface engineering, we unravel the mechanism of superconductivity that originates from a two-dimensional electron gas formed at the interface of SnSe2 and graphene. Our finding opens up novel strategies to hunt for and understand interface superconductivity based on van der Waals heterostructures.
关键词： two-dimensional electron gas,interface superconductivity,van der Waals heterostructure,SnSe2,graphene
更新于2025-09-04 15:30:14