Enhancing redshift phenomenon in time-resolved photoluminescence spectra of AlGaN epilayer

Abstract

AlGaN epitaxial layer has been studied by means of temperature-dependent time-integrated photoluminescence (PL) and time-resolved photoluminescence (TRPL). An enhancing redshift phenomenon in TRPL spectra with increasing temperature was observed, and the localized excitons behaved like quasi two-dimensional excitons between 6 K and 90 K. We demonstrated that these behaviors are caused by a change in the carrier dynamics with increasing temperature due to the competition of carriers' localization and delocalization in the AlGaN alloy.

A newly designed femtosecond KBe2BO3F2 device with pulse duration down to 55 fs for time- and angle-resolved photoemission spectroscopy

“…Our work extends the application of KBBF crystal to high time resolution TrARPES measurements with tunable VUV probe source, with performance exceeding the conventional BBO-based TrARPES, thus opening up new opportunities for investigating the ultrafast dynamics of 3D quantum materials. Such fs KBBF device can also be extended to other applications [9] where ultrafast VUV source is important, such as time-resolved photoluminescence spectroscopy (PL) [53], time-resolved photoemission electron microscopy (PEEM) [8], photoassisted scanning tunnelling microscopy (STM) [54], time-resolved Raman spectroscopy [55,56] with ultimate time resolution.…”

The optical properties of 325 nm AlGaN grown by MBE

“…The radiative efficiency, which quantifies the generation of UV photons through radiative recombination in relation to competing non-radiative processes, plays a crucial role [14]. Non-radiative recombination centers, including threading dislocations and point defects arising from varied growth conditions or lattice mismatch, can hamper the quantum efficiency of AlGaN devices [15][16][17][18]. Consequently, the optimization of AlGaN-based LEDs necessitates a thorough understanding of material quality and optical characterization.…”

Time-resolved spectroscopy for 5s′ 4 D 7/2 state transitions undergoing electron–ion recombination in femtosecond laser-produced copper plasma

“…The relevant diagnoses of these ultrafast processes are usually carried out by using time-resolved measuring methods, in order to obtain the dissociation fragments and electronic momentum distributions. [7][8][9][10][11][12][13][14] The time-resolved probe method has been widely used for the investigation of various ultrafast phenomena, such as the process of material ejection by time-resolved shad-owgraph method, [15] the population of electron transition by time-resolved atom/molecule emission, [16] the ultrafast dynamics of electron transfer by fs-laser stimulated Raman spectroscopy, [17] the transient resonance line of Ca + in Ca plasma by time-resolved spectroscopy, [18] the enhancing redshift phenomenon by time-resolved photoluminescence spectrum, [19] and so on.…”