Exploration of exciton dynamics in GaTe nanoflakes via temperature- and power-dependent time-resolved photoluminescence spectra

Abstract

GaTe nanoflakes have been receiving much research attention recently due to their applications in optoelectronic devices, such as anisotropic non-volatile memory, solar cells, and high-sensitivity photodetectors from the ultraviolet to the visible region. Further applications, however, have been impeded due to the limited understanding of their exciton dynamics. In this work we perform temperature- and power-dependent time-resolved photoluminescence (PL) spectra to comprehensively investigate the exciton dynamics of GaTe nanoflakes. Temperature-dependent PL measurements manifest that spectral profiles of GaTe nanoflakes change dramatically from cryogenic to room temperature, where the bound exciton and donor-to-acceptor pair transition normally disappear above 100 K, while the charged exciton survives to room temperature. The lifetimes of these excitons and their evolution vs temperature have been uncovered by time-resolved PL spectra. Further measurements reveal the entirely different power-dependent exciton behaviors of GaTe nanoflakes between room and cryogenic temperatures. The underlying mechanisms have been proposed to explore the sophisticated exciton dynamics within GaTe nanoflakes. Our results offer a more thorough understanding of the exciton dynamics of GaTe nanoflakes, enabling further progress in engineering GaTe-based applications, such as photodetectors, light-emitting diodes, and nanoelectronics.

Efficient van der Waals layered gallium telluride-based passive photodetectors for low-power-density sensing of visible light

“…2b), which is the same as the previously identified PL peak for monoclinic GaTe at room temperature (300 K). 19,20,22–25,48 This peak is mainly attributed to the band-edge exciton emission of GaTe as confirmed by band gap measurements using micro-thermoreflectance, 19,23 absorbance, 49 and transmittance 23 spectroscopies. For more comprehensive elemental and chemical composition analyses of the vdW layered GaTe single crystals, Fig.…”

“…The detected peaks agree with several other Raman spectra of monoclinic GaTe from other works. 19,20,[22][23][24]26 According to some reports, the two peaks at B126 cm À1 and B146 cm À1 are the Raman vibration modes of hexagonal GaTe, 19,21 while other papers claim that it is due to the degradation and oxidation of GaTe when exposed to an ambient air environment. 25,48 The Raman spectrum in Fig.…”

“…[14][15][16][17][18] Among these materials is gallium telluride (GaTe), a semiconductor compound having a direct band gap of B1.65 eV at room temperature. GaTe exists in both monoclinic [19][20][21][22] and hexagonal phases, 19,21 with the former phase being more commonly reported. It is known that monoclinic GaTe has a direct band gap and a strong photoluminescence (PL) peak at B1.65 eV at room temperature, 19,20,[22][23][24] making it ideal for applications in optoelectronics.…”

“…GaTe exists in both monoclinic [19][20][21][22] and hexagonal phases, 19,21 with the former phase being more commonly reported. It is known that monoclinic GaTe has a direct band gap and a strong photoluminescence (PL) peak at B1.65 eV at room temperature, 19,20,[22][23][24] making it ideal for applications in optoelectronics. Recent studies on GaTe have focused mainly on optical anisotropy studies 19,[21][22][23]25,26 and some applications in energy storage devices such as supercapacitors 27 and photovoltaic devices.…”

Cost-efficient single photon-sensitive nanosecond gated spectrometer based on commercial grade image intensifier

“…Time-resolved spectroscopy of organic and inorganic materials is of high importance for the improvement and development of optoelectronic devices and scintillators [1][2][3][4][5][6]. Typically, high repetition rate pulses are applied to the material and then photoluminescence (PL) spectra decays are monitored [7][8][9]. The intensity of PL and its decay time can be in wide ranges, thus needing a sensitive and complicated tool for its detection.…”