| Two-dimensional semiconductor materials have excellent electronic and optoelectronic properties,and are considered as the most likely new generation materials to replace silicon-based materials.Indium selenide(In2Se3)is an attractive III-VI binary chalcogenide with crystal polymorphism and various electronic properties.The direct bulk band gap(2.09 e V)of?-In2Se3allows both a high absorption coefficient and efficient generation of electron–hole pairs under photo-excitation,which has attracted great attention in applications such as photovoltaics and photodetectors.It is considered as a promising material for photovoltaic devices,optoelectronics,phase change memories and ion batteries.In this paper,a high-performance phototransistor detector based on?-In2Se3film is constructed by introducing the built-in electric field,which significantly improves the device performance and has been successfully applied to heart rate detection.The specific research results are as follows:In2Se3film was deposited on Si O2/Si substrate by magnetron sputtering using high purity In2Se3target.Raman spectra revealed the pure phase of?-In2Se3film.AFM images showed that the?-In2Se3film had a relatively flat surface with the root mean square roughness of about 1.8 nm and the thickness of about 61 nm.?-In2Se3/Si heterojunction phototransistor was fabricated.Electrical characterization shows that the device has a wide light response in the range of365-970 nm under the effect of the built-in electric field between?-In2Se3and Si.At the same time,the performance of the device has been greatly enhanced.Compared with the control device,the photocurrent has increased by nearly two orders of magnitude,and the dark current has decreased by one order of magnitude.The responsivity and specific detectivity at 450 nm are 10.24 A/W and 3.26×1013Jones,respectively.The device also presents a fast response speed(0.76/0.85 ms for rise time?r/fall time?f).The heart rate detection was successfully realized by using?-In2Se3phototransistor detector to collect light information of 660 nm LED light passing through fingers.Compared with the heart rate measured by commercial wristband such as mi band,the deviation of the detected heart rate by this detector is less than 1,which indicates that it performs well in accurate heart rate detection and shows its potential application in real-time health monitoring.In summary,the phototransistor based on?-In2Se3film presents a remarkably improved performance such as high responsivity,low dark current,high switching ratio and fast response speed,which shows potentional application in real-time health monitoring such as heart rate detection. |
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