Types Of Photodetectors Research Articles

A universal optoelectronic imaging platform with wafer-scale integration of two-dimensional semiconductors

Photodetectors (PDs) are crucial in modern society, as they enable the detection of a diverse range of light-based signals. With the exponential increase in their development, materials are being used to create a wide range of PDs that play critical roles in enabling various applications and technologies. Image sensor technology has been hindered due to the lack of a universal system that can integrate all types of PDs with silicon-based readout integrated circuits (ROICs). To address this issue, we conducted experiments using two-dimensional materials as an example. We fabricated high-performance MoS2/MoTe2-based photodetectors and identified the most suitable ROICs to pair with them. This established a solid foundation for further research in the field of image sensors. We developed and implemented a versatile testing system that uses a printed circuit board to connect the PD and ROIC. After the ROIC generates the sampled signal, it is collected and processed by algorithms, which overcome device uniformity limitations and produce a high-quality image that is visible to the naked eye. This universal system can be used with a wide range of PD and ROIC types made from different materials, making it highly convenient for diverse testing applications and the development of diverse image sensor types. This robust new platform is expected to spur further innovation and advancements in this rapidly developing field.

High-Performance Ultraviolet Photodetectors Based on Nanoporous GaN with a Ga2O3 Single-Crystal Layer.

The utilization of a nanoporous (NP) GaN fabricated by electrochemical etching has been demonstrated to be effective in the fabrication of a high-performance ultraviolet (UV) photodetector (PD). However, the NP-GaN PD typically exhibits a low light-dark current ratio and slow light response speed. In this study, we present three types of UV PDs based on an unetched GaN, NP-GaN distributed Bragg reflector (DBR), and NP-GaN-DBR with a Ga2O3 single-crystal film (Ga2O3/NP-GaN-DBR). The unetched GaN PD does not exhibit a significant photoresponse. Compared to the NP-GaN-DBR PD device, the Ga2O3/NP-GaN-DBR PD demonstrates a larger light-dark current ratio (6.14 × 103) and higher specific detectivity (8.9 × 1010 Jones) under 365 nm at 5 V bias due to its lower dark current (3.0 × 10-10 A). This reduction in the dark current can be attributed to the insertion of the insulating Ga2O3 between the metal and the NP-GaN-DBR, which provides a thicker barrier thickness and higher barrier height. Additionally, the Ga2O3/NP-GaN-DBR PD device exhibits shorter rise/decay times (0.33/0.23 s) than the NP-GaN-DBR PD, indicating that the growth of a Ga2O3 layer on the DBR effectively reduces the trap density within the NP-GaN DBR structure. Although the device with a Ga2O3 layer presents low photoresponsivity (0.1 A/W), it should be feasible to use Ga2O3 as a dielectric layer based on the above-mentioned reasons.

Nitrocellulose‐Passivated SnO2 Thin Film as a Ultraviolet‐C Photodetector

This study demonstrates the development of an ultraviolet (UV)‐C photodetector (PD) fabricated using a surface‐passivated SnO2 thin film deposited via spray pyrolysis. This PD possesses an unprecedentedly fast response speed, with both rise time and decay time of 0.3 ms. Furthermore, even when subjected to a modest UV light intensity of 6 μW cm−2, the device shows a significantly high responsivity of 1500 A W−1, external quantum efficiency of 7 × 105%, and detectivity of 1013 Jones. When compared to previously reported SnO2‐based PDs, this device exhibits consistent performance over a long working time, which may be due to the suppression of surface vacancy defects via surface passivation, as observed from structural and optical measurements. This type of PDs has the potential to be useful in wide range of applications, including industrial sensing, medical diagnostics, and environmental monitoring.

Dual-polarity response in self-powered ZnO NWs/Sb2Se3 film heterojunction photodetector array for optical communication

Abstrct Self-powered photodetectors (PD) have great potential applications in visible light communication (VLC) systems due to their unique advantages such as energy saving and low cost, where color shift keying (CSK) is widely utilized to meet the requirements of non-negative light intensity modulation. However, at least two PDs with filters are needed to decode the optical signals, greatly increasing the device cost and complicating the communication system. Here, we report a new type of dual-polarity response PD with an adjustable polarity switching wavelength, where the output signals are positive and negative in long and short wavelength regions, respectively. The dual-polarity response is a consequence of the competition between photovoltaic (PV) effect of ZnO NWs/Sb2Se3 film p-n junction and pohtothermoelectric (PTE) effect of Sb2Se3 thin film. As compared with current PDs in CSK systems, our PD can work without any filter and one PD can realize the function of two traditional PDs. This new PDs have the potential applications in optical communication systems and filterless color discrimination.

Effect of substrate orientation on Sb-based MWIR photodetector characteristics

Effects of GaSb substrate orientation and surface polarity on performance of MWIR photodetectors (PD) were evaluated by comparing devices fabricated on (1 0 0), (2 1 1)A and B, and (3 1 1)A and B oriented substrates. Two types of PDs were evaluated: bulk InAsSb barrier PD with wavelength ∼4 µm, and type-II strained layer superlattice (T2SL) PD with wavelength 5.5 µm. Epitaxial structures were grown by solid source molecular beam epitaxy (MBE) on substrates with various orientations side-by-side in the same growth run. Material performance was evaluated by AFM, Nomarski microscopy, x-ray diffraction, 77 K photoluminescence (PL), and PD current-voltage and spectral testing. All wafers demonstrated reasonable surface morphology, with some variability in roughness from wafer to wafer. Bulk nBn devices fabricated on the high-index substrates show a blue shift up to 0.15 µm for both 77 K PL and for spectral cutoff wavelength compared to the same structure on the (1 0 0) substrate. Growth on high-index substrates also showed moderate reduction of quantum efficiency (QE) and variations in dark current (Jd). The (3 1 1)A and (2 1 1)A oriented structures exhibited the most significant Jd reduction, by a factor of ∼3 and ∼6, respectively. Substrate orientation induces more variation in the T2SL PD parameters, especially in Jd and QE. Here, the (2 1 1)B orientation demonstrates a red shift of the PL and cutoff wavelength by about 1 µm. These results suggest that high-index substrates can be explored to fine-tune and manipulate unique PD characteristic properties for specific applications.

Evaluation of different photodetector types for an ILC polarimeter

At the International Linear Collider (ILC) (ILC Reference Design Report, 2007 〈 http://www.linearcollider.org/rdr 〉 [2]) the polarization of the electron and positron beams needs to be measured with as yet unequaled precision of Δ P / P ≈ 0.25 % . The key element of the polarimeter will be the precise detection of Cherenkov light from Compton scattered electrons. The poster 〈 http://ndip.in2p3.fr/ndip08/Poster/P3/66-Helebrant.pdf 〉 [1]) deals with the choice of a suitable photodetector (PD). In a recently assembled test facility various types of PDs have been checked. Results are presented with a special focus on the linearity of the device, since this is expected to be the limiting factor on the precision of the polarization measurement at the ILC.