Magnetic-Field-Induced Delocalized to Localized Transformation in GaAs:N

Abstract

The use of a high magnetic field (57 T) to study the formation and evolution of nitrogen (N) cluster and supercluster states in GaAs:N is demonstrated. A magnetic field is used to lift the conduction band edge and expose resonant N cluster states so that they can be directly experimentally investigated. The reduction of the exciton Bohr radius also results in the fragmentation of N supercluster states, enabling a magnetic field induced delocalized to localized transition. The application of very high magnetic fields thus presents a powerful way to probe percolation phenomena in semiconductors with bound and resonant isoelectronic cluster states.

Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states

“…It is also evident from Figs. 2 and 3 that the localized states within the defect band continuously (in energy) merge with the delocalized (supercluster) 17 states. The value of energy where this transition occurs is marked with an arrow in Figs.…”

“…[1][2][3][4][5]10 After 15 years of intensive study, the recent interest in GaAs 1Àx N x has shifted to focusing on N concentrations less than 0.5% for understanding how the band structure evolves as one goes from the very heavy doping (parts per hundred thousand) to the dilute alloy (parts per hundred) limit. [14][15][16][17][18][19] This paper discusses the nature of light emitting states in ultra-dilute GaAs 1Àx N x observed through a very complex emission spectrum. We will present strong evidence for the existence of both localized and delocalized states within the continuum of states forming the defect band, [18][19][20] address the controversy whether the low energy peaks in the emission spectra are phonon-assisted transitions or from a separate set of cluster states, [21][22][23] and finally discuss the quantum mechanical enhancement of the excitonic oscillator strength on account of the localization of its center of mass.…”

Magnetoreflection spectroscopy of monolayer transition-metal dichalcogenide semiconductors in pulsed magnetic fields

“…In this case, a fiber-coupled probe of the type described above typically suffices to obtain high quality spectra that are largely free from mechanical vibrations and subsequent misalignment during the magnet pulse. Similar fiber-coupled probe designs have been successfully used in conjunction with pulsed magnets to study mm-squared samples of magnetic semiconductors [32,33], quantum wells [34,35], colloidal quantum dots [36,37], carbon nanotubes [38,39], and polymers [40].…”

Excitonic mobility edge and ultra-short photoluminescence decay time in n-type GaAsN

“…Di erent methods have been applied on the system GaAsN in order to determine the electron e ective mass. A decrease 13 , an increase 14 16 and a non-monotonic dependence 17 of the electron e ective mass with increasing N content were observed. Using cyclotron resonance absorption spectroscopy, we found a moderate increase of the electron e ective mass with increasing N content 18 .…”