Hybrid 2D/3D Graphitic Carbon Nitride-Based High-Temperature Position-Sensitive Detector

Ultraviolet position-sensitive detectors(PSDs)are expected to undergo harsh environments,such as high temperatures,for a wide variety of applications in military,civilian,and aerospace.However,no report on relevant PSDs operating at high temperatures can be found up to now.Herein,we design a new 2D/3D graphitic carbon nitride(g-C_(3)N_(4))/gallium nitride(GaN)hybrid heterojunction to construct the ultraviolet high-temperature-resistant PSD.The g-C_(3)N_(4)/GaN PSD exhibits a high position sensitivity of 355 mV mm^(-1),a rise/fall response time of 1.7/2.3 ms,and a nonlinearity of 0.5%at room temperature.The ultralow formation energy of-0.917 eV atom^(-1)has been obtained via the thermodynamic phase stability calculations,which endows g-C_(3)N_(4)with robust stability against heat.By merits of the strong built-in electric field of the 2D/3D hybrid heterojunction and robust thermo-stability of g-C_(3)N_(4),the g-C_(3)N_(4)/GaN PSD delivers an excellent position sensitivity and angle detection nonlinearity of 315 mV mm^(-1)and 1.4%,respectively,with high repeatability at a high temperature up to 700 K,outperforming most of the other counterparts and even commercial silicon-based devices.This work unveils the high-temperature PSD,and pioneers a new path to constructing g-C_(3)N_(4)-based harsh-environment-tolerant optoelectronic devices.

Ultrasensitive broadband position-sensitive detector based on graphitic carbon nitride

As a typical two-dimensional material,graphitic carbon nitride(g-CN)has attracted great interest because of its distinctive electronic,optical,and catalytic properties.However,the absence of a feasible route toward large-area and high-quality films hinders its development in optoelectronics.Herein,high-quality g-CN films have been grown on Si substrate via a vapor-phase transport-assisted condensation method.The g-CN/Si heterojunction shows an obvious response to ultraviolet–visible-near infrared photons with a responsivity of 133 A·W−1,which is two orders of magnitude higher than the best value ever reported for g-CN photodetectors.A position-sensitive detector(PSD)has been developed using the lateral photovoltaic effect of the g-CN/Si heterojunction.The PSD shows a wide response spectrum ranging from 300 to 1,100 nm,and a position sensitivity and rise/decay time of 395 mV·mm−1 and 3.1/50μs,respectively.Moreover,the application of the g-CN/Si heterojunction photodetector in trajectory tracking and acoustic detection has been realized for the first time.This work unveils the potential of g-CN for large-area photodetectors,and prospects for their applications in trajectory tracking and acoustic detection.

Ultra-sensitive flexible Ga_(2)O_(3)solar-blind photodetector array realized via ultra-thin absorbing medium

The quest for solar-blind photodetectors with outstanding optoelectronic properties and weak signals detection capability is essential for their applications in the field of imaging,communication,warning,etc.To date,Ga_(2)O_(3)has demonstrated potential for high-performance solar-blind photodetectors.However,the performance usually decays superlinearly at low light intensities due to carrier-trapping effect,which limits the weak signal detection capability of Ga_(2)O_(3)photodetectors.Herein,a Ga_(2)O_(3)solarblind photodetector with ultra-thin absorbing medium has been designed to restrain trapping of photo-generated carriers during the transporting process by shortening the carrier transport distance.Meanwhile,multiple-beam interference is employed to enhance the absorption efficiency of the Ga_(2)O_(3)layer using an Al/Al_(2)O_(3)/Ga_(2)O_(3)structure.Based on the ultra-thin absorbing medium with enhanced absorption efficiency,a 7×7 flexible photodetector array is developed,and the detectivity can reach 1.7×10^(15)Jones,which is among the best values ever reported for Ga_(2)O_(3)photodetectors.Notably,the performance of the photodetector decays little as the illumination intensity is as weak as 5 nW/cm2,revealing the capacity to detect ultra-weak signals.In addition,the flexible photodetector array can execute the functions of imaging,spatial distribution of light source intensity,real-time light trajectory detection,etc.Our results may provide a route to high-performance solar-blind photodetectors for ultra-weak light detection.

Fabry-Perot interference and piezo-phototronic effect enhanced flexible MoS_(2) photodetector

Flexible photodetectors(PDs)are indispensable components for next-generation wearable electronics.Recently,two-dimensional(2D)materials have been implemented as functional flexible optoelectronic devices due to their characteristics of atomically thin layers,excellent flexibility,and strain sensitivity.In this work,we developed a flexible photodetector based on MoS_(2)/NiO heterojunction,and Fabry-Perot(F-P)and piezo-phototronic effect have been employed to enhance the responsivity(R)and external quantum efficiency(EQE)of the devices.The F-P effect is utilized to improve the optical absorption of the MoS_(2),resulting in an enhancement in the photoluminescence(PL)of monolayer MoS_(2) and the EQE of the photodetector by 30 and 130 times,respectively.The flexible photodetector exhibits an ultrahigh detectivity(D*)of 2.6×10^(14) Jones,which is the highest value ever reported for flexible MoS_(2) PDs.The piezo-potential of monolayer MoS_(2) decreases the valence band offset at the interface of MoS_(2)/NiO,which increases the transfer efficiency of the photon-generated carriers significantly.Under 1.17%tensile strain,the R of the flexible photodetector can be enhanced by 271%.This research may provide a universal strategy for the design and performance optimization of 2D materials heterostructures for flexible optoelectronics.

Ultrasensitive monolayer-MoS_(2) heterojunction photodetectors realized via an asymmetric Fabry-Perot cavity

Two-dimensional(2D)materials have attracted significant attention as a promising candidate for electronic and optoelectronic devices.However,low absorption impairs the performance of few-layer 2D material-based photodetectors(PDs).Herein,we purpose an asymmetric Fabry-Perot cavity consisting of a dielectric layer and metallic film to enhance the interactions between light and monolayer molybdenum disulfide(MoS_(2)).The external quantum efficiency of the monolayer MoS_(2)heterojunction PD is enhanced by more than two orders of magnitude via optimizing the thickness of the dielectric layer.The monolayer-MoS_(2)/nickel oxide heterojunction PD exhibits a large on/off ratio of 2×10^(5),a responsivity of 703 A W^(-1),and an ultrahigh detectivity of 1.31×10^(15)Jones.The detectivity is the best value ever reported for monolayer-MoS_(2)heterojunction PDs.Our results may pave the way for high-performance 2D materialbased PDs.