Synthesis of Multilayer InSe0.82Te0.18 alloy for high performance near-infrared photodetector
Graphical abstract
Introduction
Photodetector has attracted a significant attention due to its wide applications in imaging, sensor, communication and health monitoring [[1], [2], [3], [4], [5], [6]]. For developing high performance of photodetector, various types of materials have been discovered. The rise of two-dimensional (2D) and thin-film materials has provided more options for designing novel and high performance photodetection devices. Most attentions have been focused on black phosphorous (BP) [7] and transition metal dichalcogenides (TMDs) [[8], [9], [10]]. However, instability hinders BP potential application and TMDs show narrow detection range due to their large bandgaps. Indium selenide (InSe), an interesting III-VI group layered semiconductor, has attracted increasing attention due to its excellent optical and electrical properties [[11], [12], [13], [14], [15], [16], [17]]. Because of its small bandgap (1.26 eV) and high absorption coefficient, photodetector based on few-layered InSe show a broad photoresponse to visible to NIR region (450–785 nm) and high photoresponsivity [14]. The photodetection performance can be effectively regulated by optimizing channel thickness [18] and contact electrode [19], and the responsivity increases to 105 A/W for graphene-InSe-graphene device illuminated by 633 nm laser [19]. Those result demonstrate that InSe is good candidate for high performance optoelectronic devices, such as photodetector and photodiode. Indium telluride (InTe), an important member of III-VI group family with a small direct bandgap [20], has been limited. Up to now, there is no experimental studies on 2D or multilayer InTe [21]. Theory calculation demonstrates that InSe–InTe heterostructure is a good candidate for solar cell and light emission applications [22].
Alloy engineering is an important and effective tool to adjust energy band structure, optical and electrical properties of materials, and has successfully been applied in modern semiconductor field. Recently, alloy engineering also has been applied to 2D layered TMDs system [[23], [24], [25], [26]] and photoresponse of TMDs alloys is significantly improved by alloy engineering due to shifting the deep-level defect states to shallow-level defect states [25]. Compared to TMDs system, alloy engineering is limited for investigation of optoelectronic and electrical properties of InSe-based alloy materials [27,28]. Though the tunable optical bandgaps of InSe1-xSx (x ≤ 0.3) alloys [24] and superior second harmonic generation (SHG) performance in InSe0.9Te0.1 and InSe1-xSx (x = 0.1 and 0.2) alloys [28] have been demonstrated, the study on optoelectronic properties of InSe-based alloys is still absent. The improvement photoresponse of transition metal dichalcogenides (TMDs) by alloy engineering is attributed to suppression of deep-level defect states [25]. 2D Ga0.84In0.16Se alloy photodetector show superior performance than 2D GaSe photodetector for detecting visible light [29]. Those studies suggest that alloy engineering holds great potential in enhancing photodetection performance of multilayer InSe device and it is of interest to explore optoelectronic properties of InSe1-xTex alloys.
In this work, for the first time, we fabricated multilayer InSe0.82Te0.18 alloy photodetector and studied the photodetection performance of multilayer InSe0.82Te0.18 alloy. The multilayer InSe0.82Te0.18 alloy shows a broader photoresponse region of 400–1100 nm than that of multilayer InSe device, which is due to its smaller direct bandgap of 1.13 eV. The multilayer InSe0.82Te0.18 alloy photodetector shows a higher photodetection performance than InSe device and the R values are significantly enhanced by 50–300 times, especially in NIR light region. Moreover, the multilayer InSe0.82Te0.18 alloy photodetector shows a good photoresponse stability and fast photoresponse time. This work suggests that InSe0.82Te0.18 alloy is a potential material for application in NIR photodetector.
Section snippets
Synthesis of bulk InSe0.82Te0.18 alloy
Bulk InSe0.82Te0.18 crystals were prepared by the following procedure: Indium (114.8 mg, 99.99%, Aladdin) (0.001 mol) and selenium-tellurium mixture (97 mg, 71.1% Se and 28.9% Te by weight, 99.99%, Alfa) were put in quartz boat, respectively. Then the boat was placed into a one-zone horizontal furnace with a fused silica tube. The close system was purged with 300 sccm Ar gas for 30 min. Firstly, the boat was heated to 573 K and kept at 573 K for 1 h with 100 sccm Ar/H2 (VAr: VH2 = 80:20) as
Results and discussions
The synthesized process of bulk InSe1-xTex alloy was described in experimental methods. Firstly, the crystal structure of as-synthesized bulk crystal was identified by X-ray diffraction (XRD) as shown in Fig. 1a. The main peaks are consistent with standard date file PDF#34–1341, which is hexagonal structure of InSe. The other minor peaks shown in XRD pattern are belonged to InTe [28]. The XRD pattern agrees well with early report of InSe1-xTex alloy, demonstrating that bulk InSe1-xTex alloy is
Conclusions
In summary, the multilayer InSe0.82Te0.18 alloy photodetector was fabricated and the photoresponse of multilayer InSe0.82Te0.18 alloy was studied for the first time. Compared to multilayer InSe, the multilayer InSe0.82Te0.18 alloy shows a broader photoresponse from visible light (400 nm) to NIR light (1100 nm), which is due to its smaller direct bandgap of 1.13 eV. The multilayer InSe0.82Te0.18 alloy photodetector exhibits higher photodetection performance than InSe device and the R values are
Notes
The authors declare no any competing financial interest.
Acknowledgment
We gratefully acknowledge the support from the National Natural Science Foundation of China (NSFC, No. 51802038), the China Postdoctoral Science Foundation (No. 2019T120246, 2018M630329) and Heilongjiang Postdoctoral Special Fund (No. LBH-TZ1801).
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M. Yu and H. Li contributed equally to this work.