Observation of high Rydberg states of one-dimensional excitons in GaAs quantum wires by magnetophotoluminescence excitation spectroscopy

Abstract

We have studied the higher Rydberg states of the ground exciton in T-shaped GaAs quantum wires with low-temperature photoluminescence excitation spectroscopy under magnetic fields. The peak of the second even-parity Rydberg state appears and grows in intensity at the onset of the one-dimensional (1D) continuum edge under strong magnetic fields. In stark contrast to the ground exciton, it shows significantly low zero-field oscillator strength and a large diamagnetic shift. These characteristic features are attributed to the extremely weakly bound wave function of the second Rydberg state, reflecting the inherent and novel character of 1D excitons that was predicted theoretically.

Observation of excited-state excitons and band-gap renormalization in hole-doped carbon nanotubes using photoluminescence excitation spectroscopy

“…PLE spectroscopy is a powerful tool for probing the higher electronic structure of a material. [4][5][6][26][27][28] One-photon PLE spectra of the E 11 photoluminescence (PL) intensity were obtained using a tunable Ti-sapphire laser (700-1000 nm) and a liquid nitrogen cooled InGaAs diode array. Two-photon PLE spectra were performed using a wavelength-tunable femtosecond laser system (200 fs pulse duration and 200 kHz repetition rate) and a cooled InGaAs photomultiplier with a conventional time-correlated single-photon counting setup.…”

Chemical doping-induced changes in optical properties of single-walled carbon nanotubes

“…For the SDS-HiPCO samples, a large background and two broad absorption bands are observed at around 1.1 and 1.3 eV, because SDS has no chiral selectivity. On the other hand, for the PFO-HiPCO samples, because of the high selectivity of PFO, a small background and five distinguishable absorption peaks are observed at 0.920, 0.965, 1.035, 1.092, and 1.185 eV, corresponding to the E 11 excitons for (9, 7), (8,7), (8,6), (7,6), and (7, 5) SWCNTs, respectively. 43) A continuous-wave (cw) 633 nm helium-neon laser and a cw 715 nm titanium-sapphire (Ti:S) laser were used in the PL measurements for SWCNTs doped with reducing and oxidizing agents, respectively.…”

“…1(b). These spectra have four other PL peaks at 0.92, 0.97, 1.04, and 1.10 eV, corresponding to the E 11 excitons for (9, 7), (8,7), (8,6), and (7, 6) SWCNTs, respectively. 43) The PL intensity shows a drastic decrease with increasing dopant concentration, as reported in previous works.…”

“…However, the fabrication of high-quality 1D quantum wires is very difficult compared with the fabrication of zero-dimensional quantum dots. T-shaped GaAs 1D quantum wires with atomically smooth interfaces, [3][4][5][6][7] and structure-controlled organic polymers and oligomers [8][9][10] have been used previously as 1D materials for experimental studies. However, GaAs wires have been fabricated using sophisticated molecular beam epitaxy techniques at great cost and efforts, and organic polymer wires have local structural disorder and are easily damaged under light illumination in air.…”

Spin–orbit interaction effect on the linear and nonlinear properties of quantum wire in the presence of electric and magnetic fields

“…The nonlinear properties such as optical absorption and refractive index changes in these low dimensional structures have attracted much attention because of having high potentiality for device applications in photodetectors [6], far-infrared laser amplifiers [7] and high speed electro-optical modulators [8]. Recently, there has been significant research on semiconductor quantum wire (QW), especially the experimental and theoretical investigation of magnetic field on their optical properties [9,10]. Further, the energy spectrum tuneability by the effective radius and external electric and magnetic fields in QW have made it a very strong candidate for study of linear and nonlinear properties for device applications and are extensively investigated [11,12].…”