Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Abstract

Two-dimensional layered gallium monochalcogenide (GaX, where X = S, Se, Te) semiconductors possess great potential for use in optoelectronic and photonic applications, owing to their direct band edge. In this work, the structural and optical properties of full-series multilayer GaTe1−xSex for x = 0 to x = 1 are examined. The experimental results show that the whole series of GaTe1−xSex layers may contain one hexagonal (H) phase from GaTe to GaSe, whereas the monoclinic (M) phase predominates at 0 ≤ x ≤ 0.4. For x ≥ 0.5, the H-phase dominates the GaTe1−xSex series. The micro-photoluminescence (μPL) results indicate that the photon emission energy of M-phase GaTe1−xSex increases as the Se content increases from 1.652 eV (M-GaTe) to 1.779 eV (M-GaTe0.6Se0.4), whereas that of H-phase GaTe1−xSex decreases from 1.998 eV (H-GaSe) to 1.588 eV (H-GaTe) in the red to near-infrared (NIR) region. Micro-time-resolved photoluminescence (TRPL) and area-fluorescence lifetime mapping (AFLM) of the few-layer GaTe1−xSex series indicates that the decay lifetime of the band-edge emission of the M phase is faster than that of the H phase in the mixed alloys of layered GaTe1−xSex (0 ≤ x ≤ 0.4). On the other hand, for H-phase GaTe1−xSex, the decay lifetime of the band-edge emission also increases as the Se content increases, owing to the surface effect. The dark resistivity of GaTe1−xSex for 0.5 ≤ x ≤ 1 (i.e., predominantly H phase) is greater than that of the other instance of majority M-phase GaTe1−xSex for 0 ≤ x ≤ 0.4, owing to the larger bandgaps. The predominantly H phase GaTe1−xSex (0.5 ≤ x ≤ 1) also shows a greater photoconductive response under visible-light illumination because of the greater contribution from surface states. The superior light-emission and photodetection capability of the GaTe1−xSex multilayers (0 ≤ x ≤ 1) means that they can be used for future optoelectronic devices.

Spectrum-dependent image convolutional processing via a 2D polarization-sensitive photodetector

“…In the unpolarized measurement configuration, the Raman spectrum of GaTe0.5Se0.5 shows three distinct peaks located at 126, 224, and 301 cm -1 , respectively. The positions of these three peaks align closely with reported in prior literature 36 . The assigned modes correspond to Ag (1) , Eg, and Ag (2) modes, providing an additional confirmation of the material's classification as the 2H phase.…”

Phosphorus-Doped Multilayer In6Se7: The Study of Structural, Electrical, and Optical Properties for Junction Device

“…According to prior studies ,, as well as from the crystal morphology, In 6 Se 7 :P has a monoclinic structure with a multiline long-edge outline along the b axis. Similar to the other monoclinic structures in the III–VI semiconductors, such as GaTe , and M-GaTe 1– x Se x , the multiline edges are elongated in the b ( y ) axis.…”

“…III–VI layered semiconductors have gained significant attention due to their unique electronic and optical properties as well as specific technological applications. , The III and VI monochalcogenides possess a general chemical formula of MX, where M is a group III element (such as Ga or In), and X is a chalcogen atom (such as Te, Se, or S). − One of the most exciting properties of III–VI layered semiconductors is their direct band edge constructed in the multilayer form, − this can make them an ideal candidate for various optoelectronics applications such as solar cells, photodetectors, and light-emitting diodes. − Indium is easily oxidized and exhibits intriguing characteristics within the group III elements, especially as it forms many compounds by synthesis with group VI elements, such as In–O, , In–S, − In–Se, − and In–Te. , The formation of In–Se bonding is important in III–VI compounds, and it has been extensively studied and investigated for its derivatives in various applications. ,,− The investigation of In–Se-based materials is driven by their potential utilization in various applications, including solar cells, , Li-ion batteries, − and ionizing radiation detectors, due to their noteworthy physical features, such as optical and electrical properties . The materials of the In–Se system have also attracted considerable interest due to its intrinsic structural properties, including phase transition (transformation), multicrystalline zones consisting different phases, and structural imperfections. , Extensive research has been conducted on materials derived from the In–Se system, − and numerous works have investigated the phase diagram of the In–Se system with different stoichiometry and different modifications. − Previous investigations have reported that the presence of stable phases in this In–Se system includes the stoichiometric compositions of InSe, In 2 Se 3 , In 4 Se 3 ,…”

Growth Temperature Effects in Nanoscale-Thick GaTe Films on c-Sapphire Substrate by Molecular Beam Epitaxy: Implications for High-Performance Optoelectronic Devices

“…The Raman frequencies observed at approximately 114, 127, 142, and 196 cm –1 were identified as the A g modes, while those at 175 and 291 cm –1 were attributed to E 2g 1 and A 1g 2 , respectively. , The Raman peaks at 127 and 142 cm –1 , characteristic of h-GaTe, are distinctly observable . Simultaneously, Raman peaks at 115, 175, 196, and 291 cm –1 , corresponding to m-GaTe, are clearly evident as depicted in Figure a. − These peaks consistently exhibited intensity variations with changes in the growth temperature. Notably, the Raman peak intensities corresponding to h-GaTe (127 and 142 cm –1 ) gradually decrease with increasing growth temperature, indicating the suppression of the h-GaTe phase in the film at higher growth temperatures.…”