We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, pie...We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, piezoelectric scattering （PE）, and polar-optic phonon scattering （POP）. We find that DE and PE are the more significant limiting factors at intermediate temperatures of 40 K to 250 K, while POP becomes dominant as room temperature is approached. Detailed numerical results are presented for the change of electron mobility with respect to temperature and carrier density. We conclude that these three types of phonon scattering, which are generally determined by the material properties but not the technical processing, are hard limits to the 2DEG mobility.展开更多
The origin of the anomalous transport feature appearing at a conductance G 0.7× （2e2/h） in quasi-lD ballistic devices-the so-called 0.7 anomaly-represents a long standing puzzle. Several mechanisms have been pr...The origin of the anomalous transport feature appearing at a conductance G 0.7× （2e2/h） in quasi-lD ballistic devices-the so-called 0.7 anomaly-represents a long standing puzzle. Several mechanisms have been proposed to explain it, but a general consensus has not been achieved. Proposed explanations have been based on quantum interference, the Kondo effect, Wigner crystallization, and other phenomena. A key open issue is whether the point defects that can occur in these low-dimensional devices are the physical cause behind this conductance anomaly. Here we adopt a scanning gate microscopy technique to map individual impurity positions in several quasi-lD constrictions and correlate these with conductance characteristics. Our data demonstrate that the 0.7 anomaly can be observed irrespective of the presence of localized defects, and we conclude that the 0.7 anomaly is a fundamental property of low-dimensional systems.展开更多
基金supported in part by the Grainger Center for Electric Machinery and Electromechanics of the University of Illinois
文摘We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, piezoelectric scattering （PE）, and polar-optic phonon scattering （POP）. We find that DE and PE are the more significant limiting factors at intermediate temperatures of 40 K to 250 K, while POP becomes dominant as room temperature is approached. Detailed numerical results are presented for the change of electron mobility with respect to temperature and carrier density. We conclude that these three types of phonon scattering, which are generally determined by the material properties but not the technical processing, are hard limits to the 2DEG mobility.
基金This work was supported by the Italian Ministry of Research （Ministero dell＇Istruzione, dell＇Universitae della Ricerca （MIUR）-Fondo per gli Investimenti della Ricerca di Base （FIRB） project No. RBID08B3FM） and by the Italian Ministry of Foreign Affairs （Ministero degli Affari Esteri, Direzione Generale per la Promozione del Sistema Paese, progetto： Nanoelettronica quantistica per le tecnologie delle informazioni）. Two of us （C.R. and W.W.） thank the Swiss National Science Foundation （SNSF） financial support.
文摘The origin of the anomalous transport feature appearing at a conductance G 0.7× （2e2/h） in quasi-lD ballistic devices-the so-called 0.7 anomaly-represents a long standing puzzle. Several mechanisms have been proposed to explain it, but a general consensus has not been achieved. Proposed explanations have been based on quantum interference, the Kondo effect, Wigner crystallization, and other phenomena. A key open issue is whether the point defects that can occur in these low-dimensional devices are the physical cause behind this conductance anomaly. Here we adopt a scanning gate microscopy technique to map individual impurity positions in several quasi-lD constrictions and correlate these with conductance characteristics. Our data demonstrate that the 0.7 anomaly can be observed irrespective of the presence of localized defects, and we conclude that the 0.7 anomaly is a fundamental property of low-dimensional systems.
