빛에 의해 변조되는 금속-그래핀 컨택이 그래핀 포토디텍터의 광응답도에 미치는 영향

이창주,박홍식,심재훈 한국센서학회 2019 센서학회지 Vol.28 No.2

Graphene is recognized as a promising material for silicon photonics, since it has a wide optical-window that entirely covers the optical communication wavelength region (1.3~1.6-µm) and extremely high-carrier mobility that makes it possible to fabricate the highspeed photodetectors. However, the maximum absorbance of monolayer graphene is only 2.3%, which limits the photoresponse characteristics of graphene photodetectors. As a result, a low photoresponsivity of graphene photodetector is a critical issue limiting the use of graphene photodetectors in the optical communications field. In this paper, we investigated effects of optically-modulated metalgraphene contact on the photoresponsivity of graphene photodetectors. The optical modulation of the contact resistance mainly determined the photoresponse characteristics of graphene photodetectors. The Ni-contact graphene photodetector which has a characteristic of the significant optical modulation of metal-graphene contact showed a higher photoresponsivity than the Pd-contact device. This work will provide a way to improve the photoresponse characteristics of graphene-based photodetector and contribute to the development of high-speed/high-responsivity graphene photodetector.

Eye safety 라이다 센서용 황화납 양자점 기반 SWIR photodetector 개발

최수지,권진범,하윤태,정대웅 한국센서학회 2023 센서학회지 Vol.32 No.5

Recently, the demand for lidar systems for autonomous driving is increasing, and research on Shortwave Infrared(SWIR)photodetectors for this purpose is being actively conducted. Most SWIR photodetectors currently being developed are basedon InGaAs, and have the disadvantages of complex processes, high prices, and limitations in research due to monopoly. In addition,current SWIR photodetectors use lasers in the 905 nm wavelength band, which can pass through the pupil and cause damageto the retina. Therefore, it is required to develop a SWIR photodetector using a wavelength band of 1400 nm or more tobe safe for human eyes, and to develop a material that can replace the proprietary InGaAs. PbS QDs are group 4-6 compoundsemiconductors whose absorption wavelength band can be adjusted from 1000 to 2700 nm, and have the advantage of beingsimple to process. Therefore, in this study, PbS QDs having an absorption wavelength peak of 1415 nm were synthesized, anda SWIR photodetector was fabricated using this. In addition, the photodetector's responsivity was improved by applying P3HTand ZnO NPs to improve electron hole mobility. As a result of the experiment, it was confirmed that the synthesized PbS QDshad excellent FWHM characteristics compared to commercial PbS QDs, and it was confirmed that the photodetector had a maximumcurrent change of about 1.6 times.

MAPI 리간드 치환형 PbS 양자점 기반의 고감도 단파장 적외선 광 검출기 개발

최수지,권진범,하윤태,정대웅 한국센서학회 2024 센서학회지 Vol.33 No.2

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.

Effects of Transfer Gate on the Photocurrent Characteristics of Gate/Body-Tied MOSFET-Type Photodetector

( Juneyoung Jang ),( Sang-ho Seo ),( Jaesung Kong ),( Jang-kyoo Shin ) 한국센서학회 2022 센서학회지 Vol.31 No.1

In this study, we studied the effects of transfer gate on the photocurrent characteristics of gate/body-tied (GBT) metal-oxide semiconductor field-effect transistor (MOSFET)-type photodetector. The GBT MOSFET-type photodetector has high sensitivity owing to the amplifying characteristic of the photocurrent generated by light. The transfer gate controls the flow of photocurrent by controlling the barrier to holes, thereby varying the sensitivity of the photodetector. The presented GBT MOSFET-type photodetector using a builtin transfer gate was designed and fabricated via a 0.18-μm standard complementary metal-oxide-semiconductor (CMOS) process. Using a laser diode, the photocurrent was measured according to the wavelength of the incident light by adjusting the voltage of the transfer gate. Variable sensitivity of the presented GBT MOSFET-type photodetector was experimentally confirmed by adjusting the transfer gate voltage in the range of 405 nm to 980 nm.

The mechanism of photocurrent enhancement of ZnO ultraviolet photodetector by reduced graphene oxide

Tiantian Yang,Bin Sun,Lei Ni,Xing Wei,Tingting Guo,Zhemin Shi,Fei Han,Li Duan 한국물리학회 2018 Current Applied Physics Vol.18 No.8

An ultraviolet (UV) photodetector based on ZnO-reduced graphene oxide (ZnO-rGO) composites have been successfully fabricated. A pure ZnO photodetector was also fabricated by similar method. In comparison with the pure ZnO UV photodetector, the ZnO-rGO photodetector exhibits a much larger photocurrent and a better lightto- dark-current-ratio. The mechanism of photocurrent enhancement was investigated using I-V characteristics, photoluminescence (PL) spectra, transmittance spectra and time-dependent photocurrent analysis. Results show that the photocurrent enhancement of the ultraviolet photodetector is due to the improvement of the carrier lifetime, because the carrier recombination of ZnO were reduced by rGO. It provides a potential way to fabricate high-response UV photodetectors.

Versatile role of 2D Ti3C2 MXenes for advancements in the photodetector performance: A review

Adem Sreedhar,Qui Thanh Hoai Ta,Jin-Seo Noh 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

Nowadays, layer-structured two-dimensional (2D) Ti3C2 MXenes have been created a platform as promisingcandidates for developing next-generation photodetectors. Scalable spatial organization of Ti3C2MXenes enables responsive template at the interface of various semiconductors for significant improvementin the photodetector performance. In this review, we provide prospective discussion on geometricalpotentiality of 2D Ti3C2 MXenes to advance the current photodetector device performance. Specifically,we guide the versatility of Ti3C2 MXenes such as a metal electrode, flexible material, transparent nature,and self-power behavior during UV, visible, and broadband photodetector performance. By the excellenceof 2D Ti3C2, we begin to comprehend the Schottky barrier, built-in electric field, and van der Walls heterojunctionformation. It is imperative to understand the vast opportunities of Ti3C2 MXene-based photodetectorseven under flexible conditions, which is higher than conventional gold and graphene. Owing tothe desirable properties, Ti3C2 garnered significant progress in (i) large-size flexible photodetector formationwithout altering the structural and charge carrier properties, (ii) replacing conventional metal electrodesby electrically conductive Ti3C2 in Ti3C2-semiconductor-Ti3C2 (MX-S-MX) photodetector, and (iii)Schottky junction formation at the interface of various semiconductors. Finally, we conclude the status of2D Ti3C2 MXene applicability, challenges, and possible viewpoints for advancement in next-generationphotodetectors.

Highly Sensitive Flexible Photodetectors Based on Self-Assembled Tin Monosulfide Nanoflakes with Graphene Electrodes

Mohan Kumar, Ganesan,Fu, Xiao,Ilanchezhiyan, Pugazhendi,Yuldashev, Shavkat U.,Lee, Dong Jin,Cho, Hak Dong,Kang, Tae Won American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.37

<P>Tin monosulfide (SnS) nanostructures have attracted huge attention recently because of their high absorption coefficient, high photoconversion efficiencies, low energy cost, ease of deposition, and so on. Here, in this paper, we report on the low-cost hydrothermal synthesis of the self-assembled SnS nanoflake-like structures in terms of performance for the photodetectors. High-performance photodetectors were fabricated using SnS nanoflakes as active layers and graphene as the lateral electrodes. The SnS photodetectors exhibited excellent photoresponse properties with a high responsivity of 1.7 X 10(4) A/W and have fast response and recovery times. In addition, the photodetectors exhibited long-term stability and strong dependence of photocurrent on light intensity. These excellent characteristics were attributed to the larger surface-to-volume ratio of the self-assembled SnS nanoflakes and the effective separation of the photogenerated carriers at graphene/SnS interfaces. Additionally, a flexible photodetector based on SnS nanoflakes was also fabricated on a flexible substrate that demonstrated similar photosensitive properties. Furthermore, this study also demonstrates the potential of hydrothermal-processed SnS nanoflakes for high-performance photodetectors and their application in flexible low-cost optoelectronic devices.</P>

ε-Ga₂O₃ 박막 성장 및 MSM UV photodetector의 전기광학적 특성

박상훈,이한솔,안형수,양민,Park, Sang Hun,Lee, Han Sol,Ahn, Hyung Soo,Yang, Min 한국결정성장학회 2019 한국결정성장학회지 Vol.29 No.4

본 연구에서는 $Ga_2O_3$ 박막의 구조적 특성과 Ti/Au 전극을 증착하여 제작된 metal-semiconductor-metal (MSM) photodetector 소자의 광학적, 전기적 특성에 대해 연구하였다. 유기 금속 화학 증착법(metal organic chemical vapor deposition, MOCVD)을 이용해 서로 다른 온도에서 $Ga_2O_3$ 박막을 성장하였다. 성장온도에 따라 $Ga_2O_3$의 결정상이 ${\varepsilon}$-상에서 ${\beta}$-상으로 변화하는 것을 확인할 수 있었다. X-선 회절 분석(X-ray diffraction, XRD) 결과로 ${\varepsilon}-Ga_2O_3$의 결정구조를 확인하였고, 주사 전자 현미경(scanning electron microscopy, SEM) 이미지로 결정구조의 형성 메커니즘에 대해 논의하였다. 음극선 발광(Cathode luminescence, CL) 측정으로 $Ga_2O_3$의 발광성 천이에 관여하는 에너지 준위의 형성 원인에 대해 논의하였다. 제작된 MSM photodetector 소자의 외부 광에 대한 전류-전압 특성과 시간 의존성 on/off 광 응답 특성을 통해 ${\varepsilon}-Ga_2O_3$로 제작한 photodetector는 가시광보다 266 nm UV 파장 영역에서 훨씬 뛰어난 광전류 특성을 보이는 것을 확인하였다. In this study, we investigated the structural properties of $Ga_2O_3$ thin films and the photo-electrical properties of metal-semiconductor-metal (MSM) photodetectors deposited by Ti/Au electrodes. $Ga_2O_3$ thin films were grown at different temperatures using metal organic chemical vapor deposition (MOCVD). The crystal phase of $Ga_2O_3$ changed from ${\varepsilon}$-phase to ${\beta}$-phase depending on the growth temperature. The crystal structure of ${\varepsilon}-Ga_2O_3$ was confirmed by X-ray diffraction (XRD) analysis and the formation mechanism of crystal structure was discussed by scanning electron microscopy (SEM) images. From the results of current-voltage (I-V) and time-dependent photoresponse characteristics under the illumination of external lights, we confirmed that the MSM photodetector fabricated by ${\varepsilon}-Ga_2O_3$ showed much better photocurrent characteristics in the 266 nm UV range than in the visible range.

전송 게이트가 내장된 Gate/Body-Tied P-Channel Metal-Oxide Semiconductor Field-Effect Transistor 구조 광 검출기를 이용한 감도 가변형 능동 화소 센서

장준영 ( Juneyoung Jang ),이제원 ( Jewon Lee ),권현우 ( Hyeunwoo Kwen ),서상호 ( Sang-ho Seo ),최평 ( Pyung Choi ),신장규 ( Jang-kyoo Shin ) 한국센서학회 2021 센서학회지 Vol.30 No.2

In this study, the sensitivity of an active pixel sensor (APS) was adjusted by employing a gate/body-tied (GBT) p-channel metal-oxide semiconductor field-effect transistor (PMOSFET)-type photodetector with a transfer gate. A GBT PMOSFET-type photodetector can amplify the photocurrent generated by light. Consequently, APSs that incorporate GBT PMOSFET-type photodetectors are more sensitive than those APSs that are based on p-n junctions. In this study, a transfer gate was added to the conventional GBT PMOSFET-type photodetector. Such a photodetector can adjust the sensitivity of the APS by controlling the amount of charge transmitted from the drain to the floating diffusion node according to the voltage of the transfer gate. The results obtained from conducted simulations and measurements corroborate that, the sensitivity of an APS, which incorporates a GBT PMOSFET-type photodetector with a built-in transfer gate, can be adjusted according to the voltage of the transfer gate. Furthermore, the chip was fabricated by employing the standard 0.35 μm complementary metal-oxide semiconductor (CMOS) technology, and the variable sensitivity of the APS was thereby experimentally verified.

Design and Numerical Investigation of CsSn0.5 Ge0.5 I3 Perovskite Photodetector with Optimized Performances

Kamal Mishra,R. K. Chauhan,Rajan Mishra,Vaibhava Srivastava 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.1

An optoelectronic device to detects incident light and convert it into an electrical signal is known as a photodetector. To obtain higher responsivity and detectivity of photo detector, suitable materials are required. In the present study, an inorganic leadfree perovskite CsSn 0.5 Ge0.5 I3 material is utilized as an active layer for photodetector applications, together with Nb2 O5 as electron transport layer (ETL) and CuSbSe2 as hole transport layer (HTL). The perovskite photodetector (PePd) is simulated by employing Solar Cell Capacitance Simulator-One Dimensional (SCAPS-1D) software. We have thoroughly investigated the impact of various parameters such as the defect density and donor concentration of active layer, series and shunt resistance, the thickness of active layer and metal work function of back contact using numerical simulation. Under standard AM 1.5G irradiance, we obtained the detectivity (D*) and responsivity (R) of the proposed photodetector are 3.3 × 10 13 Jones and 0.54 AW -1 respectively. The proposed device performances reveal that it is suitable for high performance photodetector.