Investigation of Thickness-Dependent Optical and Optoelectronic Properties of Mechanically Exfoliated GaSe Nanoflakes

Abstract

Two-dimensional (2D)-layered materials are in prime focus of the researchers because of their excellent optoelectronic properties at the micro- and nanolevels. In this work, we have conducted a comprehensive study on the thickness-dependent optical and optoelectronic properties of the mechanically exfoliated GaSe thin films. Raman and photoluminescence measurements were done on the ultrathin GaSe flakes of different thicknesses to study the change in their phonon modes and optical properties. To understand the optoelectronic properties, metal–semiconductor–metal (MSM) photodetectors were fabricated on GaSe flakes. The performance of the photodetectors was measured in terms of the figure-of-merit parameters of a photodetector such as photoresponsivity (R λ) and external quantum efficiency (EQE). Thicker GaSe flakes provided better performance, with a maximum value of R λ and EQE of ∼0.21 A/W and ∼42, respectively, at 620 nm, as compared to thinner flakes. We believe our study could help to boost the development of future high-performance optoelectronic devices based on quasi-2D materials.

Wafer‐Scale Two‐Dimensional Semiconductors for Deep UV Sensing

“…We assign the smaller value of 𝜏 l /𝜏 t in the thinner layers to a larger carrier recombination rate at the sapphire-GaSe interface and lower mobility of charge carriers. Overall, the properties of these devices compare favorably with UV-sensors from the literature, such as those reported recently for the wide band gap Ga 2 O 3 , [48][49][50] whose frequency band and on/off current ratio are both smaller than in our devices. The large optical absorption of GaSe in the UV-C band (200-280 nm range) and sensitivity to polarization of light provide a platform for advances in this important technological spectral range.…”

Room-Temperature Optoelectronic NO2 Sensing Using Two-Dimensional Gallium Oxyselenides

“…Furthermore, Raman spectroscopy was employed to reveal the bonding details of gallium oxyselenide. In Figure c, the Raman spectrum of GaSe flakes displays four discernible peaks, two of which correspond to out-of-plane modes (A 1g 1 and A 1g 2 ) and the other two representing in-plane modes (E 2g 1 and E 1g 2 ). , The A 1g 1 and A 1g 2 are specifically located at approximately 130.6 and 303.3 cm –1 . Conversely, E 2g 1 and E 1g 2 are located at around 233.5 and 250.8 cm –1 , which are inconsistent with previous reports. , Upon raising the annealing temperature, a notable reduction in the intensity of peaks A 1g 1 , A 1g 2 , and E 1g 2 was observed, whereas the E 2g 1 peak displayed a minor red shift from 233.5 to 231.2 cm –1 .…”

“…2 ). 51,52 The A 1g 1 and A 1g 2 are specifically located at approximately 130.6 and 303.3 cm −1 . Conversely, E 2g…”

α-In2Se3 Nanostructure-Based Photodetectors for Tunable and Broadband Response

“…It is known that stronger optical absorption is beneficial to boost photogenerated carriers in devices, thereby improving the photocurrent and corresponding FOMs. Moreover, the difference in the channel’s conductance and the contact barrier between the metal and semiconductors with different thicknesses may also contribute to the efficiency of photodetectors. , As shown in Figure S6f, the devices’ dark current decreases with the thinning channel from 35 to 2 nm, which might result in the degradation in current carrying capacity for thin devices, leading to their low performance.…”