Ultrabroadband, Fast, and Flexible Photodetector Based on HfTe₅ Crystal

Abstract

However, rare materials have the ability directly sensitive to light over a broad range of the electromagnetic spectrum from ultraviolet (UV) down to terahertz (THz) wavelengths, particularly at room temperature. For example, conventional semiconductors such as silicon [2] and transition metal dichalcogenides, [3] which have photo response properties cut off by the bandgap, are transparent to light below their bandgap, and therefore, transparent to THz photons. Recent studies on ultrabroadband photodetectors have mainly focused on fabricating devices using graphene owing to its gapless band structure. [4] However, a significant shortcoming of graphene-based photodetectors is their low optical absorption, which is a critical obstacle for efficient photodetection. [5] To overcome this drawback, researchers have fabricated graphene quantum dot arrays, [6] and heterostructures with silicon nanowire arrays, [7] as well as monolithically integrated graphene with a Fabry-Perot microcavity, [8] to improve the responsivities. However, all these devices share a common problem-namely the complex device fabrication processes involved. Other materials such as topological insulators (TIs), which benefit from their relativistic Dirac-dispersion of the surface state, are considered promising candidates for multiband photodetection, and have attracted considerable Ultrabroad spectrum detection has a wide range of photonic and optoelectronic applications, such as spectroscopy, optical communication, imaging, and sensing. 3D topological insulator candidates are promising materials for fast high-performance photodetectors owing to their linear dispersion band structure and high carrier mobility. In this study, an ultrabroadband photothermoelectric (PTE) self-powered detector based on the topological insulator candidate HfTe 5 is reported for the first time. The photosensitive properties are characterized in an ultrabroadband range from the ultraviolet (375 nm) to terahertz (118.8 µm) wavelengths, and the responsivities at all examined wavelengths are found to be greater than 1 V W −1 at room temperature. Owing to the Dirac band dispersion of HfTe 5 , the response time (τ) of the proposed detector is as short as ≈1 ms, which is 1-3 orders of magnitude faster than that of recently reported PTE detectors based on millimeter-scale graphene, 3D graphene, EuBiSe 3 single crystal, and SrTiO 3 crystal. Furthermore, the sensitivity of the HfTe 5 detector to the light intensity and direction of linearly-polarized light is demonstrated. Thus, the proposed device demonstrates outstanding flexibility, air stability, and long-term photostability as well, displaying high potential for practical applications in wearable optoelectronics.

Highly Efficient, Ultrabroad PdSe2 Phototransistors from Visible to Terahertz Driven by Mutiphysical Mechanism

“…Based on these I – V curves, the good ohmic contact originates from the special case of nonrectifying metal–semiconductor contact, which is between the metal and low-work-function p-type semiconductor. Also, the resistance change under illumination in these curves can exclude the PTE effect, which usually results in a vertical shift with respect to the dark without changing the channel resistance. , Figure b shows the measured photocurrent spatial distribution along the channel without bias. The photocurrent was prominently generated near the electrode–PdSe 2 interfaces with opposite direction at S and D. Also, the same distribution under bias is shown in Figure S6a.…”

Organic/Inorganic Hybrid Boosting Energy Harvesting Based on the Photothermoelectric Effect

“…Note that under light illumination, these I – V curves display an obvious upward trend with respect to the ones without light illumination. This fact suggests that the as-prepared PEDOT:PSS, Te NWs, and PEDOT:PSS/Te NW hybrid films exhibit the typical photothermoelectric properties, leading to an increase in photocurrent from the separation of excited electron–hole pairs; similar phenomena can be observed for other photothermoelectric materials. , Although there are many physical mechanisms for the generation of photocurrent including photovoltaic, bolometric, and photothermoelectric effects, the induced voltage in the presence of light illumination is probably attributed to the superposition of photovoltaic and photothermoelectric effects for the hybrid film. Figure B displays the nonlinear dependence of voltage on illumination time, suggesting a result of complex processes of voltaic generation.…”

“…The excellent photoelectric and thermoelectric properties of tellurium nanowires (Te NWs) have aroused widespread concern in the field of photodetector and thermoelectric energy harvesting. − These attractive properties also imply the possible presence of a good photothermoelectric effect in Te NWs . As an alternative thermoelectric material, an obvious disadvantage of Te NWs is their very low electrical conductivity (σ), despite their considerable Seebeck coefficient ( S ).…”

Self‐Powered Light‐Temperature Dual‐Parameter Sensor Using Nb‐Doped SrTiO3 Materials Via Thermo‐Phototronic Effect

“…As known by now, the responsivity R and detectivity D * of the ITO/NSTO/ITO sensor are higher than many reported phototronic photodetectors. [ 17–19,25 ] It is worth noting that no saturation behavior or saturation signs of the photocurrent with increasing laser intensity is observed, indicating that the sensor is available to detect a stronger incident light. Furthermore, output power P of this device is investigated by analyzing the loading resistance‐dependent photocurrent.…”

“…Electric signals related to photovoltaic effect and thermoelectric effect always exhibit strong interference from each other, which is adverse to accurate and simultaneous light‐temperature sensing. Recently, a phototronic effect which involves optical‐thermal energy conversion and thermoelectric effect has attracted intensive attention and been observed in various materials, such as graphene, [ 12–15 ] black phosphorus, [ 16 ] HfTe 5 , [ 17 ] EuBiSe 3 , [ 18 ] and nanoporous Si. [ 19 ] The phototronic effect has been proven to possess the ability of realizing ultra‐broadband photodetection.…”