Asymmetric electrode incorporated 2D GeSe for self-biased and efficient photodetection

Abstract

2D layered germanium selenide (GeSe) with p-type conductivity is incorporated with asymmetric contact electrode of chromium/Gold (Cr/Au) and Palladium/Gold (Pd/Au) to design a self-biased, high speed and an efficient photodetector. The photoresponse under photovoltaic effect is investigated for the wavelengths of light (i.e. ~220, ~530 and ~850 nm). The device exhibited promising figures of merit required for efficient photodetection, specifically the Schottky barrier diode is highly sensitive to NIR light irradiation at zero voltage with good reproducibility, which is promising for the emergency application of fire detection and night vision. The high responsivity, detectivity, normalized photocurrent to dark current ratio (NPDR), noise equivalent power (NEP) and response time for illumination of light (~850 nm) are calculated to be 280 mA/W, 4.1 × 10 9 Jones, 3 × 10 7 W −1 , 9.1 × 10 −12 WHz −1/2 and 69 ms respectively. The obtained results suggested that p-GeSe is a novel candidate for SBD optoelectronics-based technologies. Two-dimensional (2D) materials have chronically been the most widely studied materials, particularly after the successful scotch tape test to exfoliate graphene by Andre Geim and Kostya Novoselov in 2004 1. 2D materials possess excellent electrical and mechanical properties toward diverse electronic device applications. Graphene, being the prototype of 2D materials 2,3 , has been studied broadly for its exotic electrical, optical, and mechanical properties 3,4. Besides, the group-IV transition metal dichalcogenides (TMDs) having a bandgap of around 1 to 2 eV 5-7 have attracted increasing interest because of their promising electronic and optoelectronic device applications 3,8-21. Graphene possesses extremely high carrier mobility (>10 5 cm 2 V −1 s −1), but the absence of band gap limits its electronic and optoelectronic applications 22. Therefore, TMDs with the properties of graphene-like stature, bandgap tunability, weak van der Waals-like forces and stability have intrigued the interest of the scientific community. TMDs are the family of 2D materials having the chemical composition of MX 2 , where M stands for the transition metal elements (M = Mo, W, Ta, Ge…etc) and X for the chalcogen elements (X = Se, S and Te). Among TMDs, Ge-based materials are preferred for applications due to their abundance on earth and environmentally friendly nature 23. With Se, the p-type Germanium from a narrow bandgap semiconductor material as p-GeSe having exciting application in near-infrared (NIR) photodetectors and electron tunnelling devices. p-GeSe has an indirect bandgap of 1.08 eV in the bulk 24,25 , and a direct bandgap of ~1.7 eV in monolayers 24,26,27. Few layers of p-GeSe can be obtained from bulk by mechanical exfoliation method 28. Among the many applications, p-GeSe shows tremendous capability in the realm of photovoltaics, because of its excellent optical, material and electrical properties. Therefore, it is well known as substitution of phosphorene 29. Moreover, GeSe is considered as an amb...

Applications of Lead‐Free Cs2AgBiBr6 Single Crystals in Photodetectors and Self‐Powered Photodetectors by Symmetric/Asymmetric Electrodes

“…[ 40,64 ] Therefore, an electric field from Au electrode to Ag electrode was built in the device, which was responsible for the self‐powered function of the device. [ 65 ] Upon illumination, photo‐induced charge carriers in the Cs 2 AgBiBr 6 SC diffused to the Schottky barrier regions and then were separated by the built‐in electric field. Afterward, Au and Ag electrodes extracted holes and electrons, respectively, generating the photocurrent at 0 V. Therefore, a self‐powered PD was fabricated by evaporating Au and Ag metal electrodes on the surface of Cs 2 AgBiBr 6 SC (Figure 4c).…”

Deep-Ultraviolet (DUV)-Induced Doping in Single Channel Graphene for Pn-Junction

“…The N 2 gas in the presence of DUV irradiation dissociates into atoms which are absorbed on the surface of the graphene. These N 2 atoms react with the oxygen atoms present on the surface of the graphene and produce O 2 molecules that are removed [24,25,[27][28][29]31,32,39]. The N 2 atoms under DUV attach to the graphene surface and become the major source of electrons, inducing higher n-type doping.…”

Engineering sensitivity and spectral range of photodetection in van der Waals materials and hybrids

“…Hence, there is a net short circuit current (refer to equation (6)) which aids in photovoltaic response. Self-driven photodetectors are currently being researched in other 2D analogues and hybrids [45,[90][91][92] 3.3. Photo-thermoelectric and Bolometric effect in Gr and TMDCs Gr is considered to be an ideal bolometric material that offers ultra-low electronic specific heat ∼10 21 J K −1 and weak electron phonon-coupling while maintaining a fast response time.…”