Carrier trapping in single quantum wells with different confinement structures

Abstract

The trapping efficiency and trapping dynamics of photoexcited carriers in GaAs/AlGaAs single quantum wells with different confinement structures are examined at low temperature by means of picosecond luminescence as well as photoluminescence excitation spectroscopy. The trapping efficiency is 100% only in graded-index separate confinement heterostructures with a linear band-gap profile. The lower trapping efficiency of other confinement structures is due to radiative and nonradiative recombination in the confinement layers.

Super‐Efficient Exciton Funneling in Layer‐by‐Layer Semiconductor Nanocrystal Structures

“…[15] However, our findings on the recycling of excitons suggest an effective way to increase the quantum efficiency. The concept of funneling is also used in electronic [28] and optoelectronic semiconductor devices made by epitaxy [29,30] and in organic optoelectronic devices. [31,32] …”

Optical properties of Zn(S,Se) sawtooth superlattices grown by atomic layer epitaxy

“…So far, similar absorption profiles were reported in graded-index separate confinement heterostructures of AlGaAs crystals. 12 Time-resolved PL spectra of STS and ͑ZnS͒ 1 ͑ZnSe͒ 4 at 2 K was also measured to determine exciton emission life time in the STS. Emission life time ͑͒ are determined by fitting the PL decay line to the theoretical curve: I(t)ϭI 0 exp͑Ϫt/͒.…”

Long-range pair transport in graded band gap and its applications

“…For example, in the GaAs quantum well, the isotropic diffusion of excitons with a diffusion length of 2 mm was spatially resolved [2]. Short-range, but very efficient pair transfer was observed in the graded band gap of the AlGaAs-based graded index separate confinement heterostructure (GRINSCH), where the exciton transfer for 200 nm occurs within 20 ps of the time resolution [3]. In this paper, the author proposes a flexible method for long-range transport of neutral electron-hole pairs (excitons).…”