High performance few-layer GaS photodetector and its unique photo-response in different gas environments

Abstract

Layered GaS nanosheets have been attracting increasing research interests due to their highly anisotropic structural, electrical, optical, and mechanical properties, which are useful for many applications. However, single-layer or few-layer GaS-based photodetectors have been rarely reported. Here a few-layer GaS two-terminal photodetector with a fast and stable response has been fabricated. It shows different photo-responses in various gas environments. A higher photo-response (64.43 A W(-1)) and external quantum efficiency (EQE) (12,621%) is obtained in ammonia (NH3) than in air or oxygen (O2). A theoretical investigation shows that the charge transfer between the adsorbed gas molecules and the photodetector leads to the different photo-responses.

Ultrathin SnSe2 Flakes Grown by Chemical Vapor Deposition for High‐Performance Photodetectors

“…[ 41,42 ] Therefore, pure photoconductive effect (with minor trapping effect) [ 43 ] might dominate the response rate here and thus fast response rate is recorded. Besides, as well known, ultrathin 2D materials with large specifi c surface area can result in higher photosensitivity and prolonged carrier lifetime of photoinduced carriers due to charge separation [ 4,10,27 ] than their bulk counterparts, which may also explain the high performance of our ultrathin SnSe 2 fl ake based photodetector. More interestingly, as reported in recent analogous works, ultrathin few layered 2D materials might even be a better choice in electronics/optoelectronics than their monolayer counterparts due to screening effects of negative infl uences, such as charged impurities or trap states, from interfaces with a substrate or electrodes.…”

“…Figure 2 a depicts the low-magnifi cation dark-fi eld TEM image of a typical SnSe 2 fl ake on the copper grid. The lattice fringes (Figure 2 b) indicate a perfect atomic structure with a lattice spacing of 0.33 nm, corresponding to the (1010) planes of 2D semiconducting materials, such as transition metal dichalcogenides (TMDs) (MoS 2 , [ 1 ] WS 2 , [ 2 ] MoSe 2 , [ 3 ] ), IIIA-VIA group (GaS, [ 4,5 ] GaSe, [ 6,7 ] InSe, [ 8,9 ] In 2 Se 3 , [ 10 ] ), and IVA-VIA group compounds (SnS 2…”

Structural and electronic properties of monolayer group III monochalcogenides

“…Among these, monolayer GaS and GaSe are great candidates for being used in photodetectors due to their strong absorption behavior in the UV-visible wavelength [27,33]. GaS sheets also have strong and unique photoresponse behavior in different gaseous environments [24]. In a theoretical study, single layer GaS and GaSe were suggested as potential photocatalysts for water splitting when the band edge position is compared with the redox potential of water [34].…”

“…To date, various MX systems such as InSe [22,23], GaS [24][25][26], GaSe [27,28], GaTe [29], and In 2 Se 3 [30,31] have been experimentally realized. Besides the fabrication, great endeavor has been dedicated to reveal the intriguing electronic and optical properties of MX and their potential applications for use in many fields [32].…”

Material and Device Architecture Engineering Toward High Performance Two-Dimensional (2D) Photodetectors

“…This complex process is mainly dependent on the inherent characteristics of the photodetector's active materials, such as absorption coefficient, lifetime of electron-hole pair and charge mobility. Several types of materials are selected and designed to satisfy the specific photoresponse, including graphene, transition metal dichalcogenides (TMDs) [17] (MoS 2 , WS 2 , MoSe 2 ), IIIA-VIA group [18,19] (GaS, GaSe, InSe, In 2 Se 3 ), IVA-VIA group compounds [20] (SnS 2 ), black phosphorus and the recently discovered all-inorganic perovskites [21,22].…”