与Si CMOS兼容的Graphene/MoS2异质结全差分光电探测器和读出电路

提出了一种基于Graphene/MoS₂异质结的全差分 光 电探测器。利用标准半导体微纳加工技术,制作了有效区域为2.3 μ m×10 μm的Graphene/MoS₂异质结结构,用以产生差 分光电流;使用0.18 μm CMOS工艺设计了差分放大与恒压控制电路 ,实现光电流到电压的转换和放大。结果表明:在白光照射 下,单个Graphene/MoS₂异质结结构光响应度达2435 A/W。差分光生电流经过差分放大器后,以电压形式输出,总光响应度加 倍。该全差分光探测器基于新型二维材料,对可见光具有较高的灵敏度,在可见光探测和成 像领域具有广阔的应用前景。     

Measurement of charge transfer potential barrier in pinned photodiode CMOSimage sensors

The charge transfer potential barrier (CTPB) formed beneath the transfer gate causes a noticeable image lag issue in pinned photodiode (PPD) CMOS image sensors (CIS), and is difficult to measure straightforwardly since it is embedded inside the device. From an understanding of the CTPB formation mechanism, we report on an alternative method to feasibly measure the CTPB height by performing a linear extrapolation coupled with a horizontal left-shift on the sensor photoresponse curve under the steady-state illumination. The theoretical study was performed in detail on the principle of the proposed method. Application of the measurements on a prototype PPD-CIS chip with an array of 160 × 160 pixels is demonstrated. Such a method intends to shine new light on the guidance for the lag-free and high-speed sensors optimization based on PPD devices.     

Van der Waals p–n Junction Based on an Organic–Inorganic Heterostructure

Organic–inorganic heterostructures are an emerging topic that is very interesting for optoelectronics. Here, non‐conventional p–n junctions are investigated using organic rubrene single crystal and 2D MoS₂ as the p‐ and n‐type semiconducting materials, respectively. The current‐rectifying behavior is clearly observed in the junction device. The rectification ratio can be electrically tuned by the gate voltage due to the 2D nature of the heterostructure. The devices also show good photoresponse properties with a photoresponsivity of ≈500 mA W^?1 and a fast response time. These findings suggest a new route to facilitate the design of nanoelectronic and optoelectronic devices based on layered inorganics and organics.     

AlGaN基p-i-n光电探测器负响应现象研究

对AlGaN基p-i-n光电探测器的负光电响应特性进行研究,从实验上证实了器件中p型接触电极的肖特基特性是导致该现象的主导因素.不同偏压下的响应光谱表明,这些AlGaN光伏器件中存在较为明显的光导响应特性.光照和暗背景条件下的C-f曲线验证了器件中的持续光电导特性,而高铝组分铝镓氮材料内存在的大量缺陷被认为是该现象的起因.系统地研究了AlGaN基p-i-n光电探测器存在的负响应现象及其微观机理,为铝镓氮基日盲器件光电性能的优化提供了重要参考依据.     

Wrinkled liquid-crystalline microparticle-enhanced photoresponse of PDLC-like films by coupling with mechanical stretching

Photoresponsive behaviors are studied in hybrid liquid-crystalline (LC) films prepared with light-responsive LC polymer microparticles as dopants using photoinert polymers as a host material. Upon mechanical stretching, both topological shape change and mesogenic alignment occur in the LC polymer microparticles, enabling the polymer-dispersed LC (PDLC)-like films to bend toward a light source upon UV irradiation. The rough morphologies of the hydrophobic LC microparticles enhance their interactions with hydrophilic polymer substrates. The bilayer-like structures of the hybrid film formed in the fabrication processes are responsible for the photomechanical behavior, which is reversibly controlled by combing light irradiation with the stretching processes.     

Photoelectrical Response in Single‐Layer Graphene Transistors

The illumination of single‐layer graphene (SLG) transistors with visible light causes a negative shift in their transfer curves, attributable to the desorption of oxygen. However, their hysteresis is not affected by illumination, which suggests that charge traps are not affected by the visible‐light exposure. When SLG transistors are covered with a layer of photoactive polymer, the photodesorption‐induced current change in the transistors becomes less significant than the effects caused by the surrounding photoactive polymer. These observations demonstrate that the photoelectrical response of SLG transistors is dominated by extrinsic mechanisms rather than by the direct photocurrent process. The results suggest a new strategy for achieving light detection. The large cross section of SLG films for receiving photons and the capability of tailoring photoelectrical properties on them is potentially useful for optoelectronic applications.     

非制冷型中长波铟砷锑探测器

工作在中、长波红外波段(波长5~12μm)的红外探测器在红外制导、红外成像、环境监测及资源探测等方面有着重要而广阔的应用前景。目前中国军用和民用对这一波段的非制冷型、快速响应的光子型红外探测器有迫切需求。文中用熔体外延(ME)法在InAs(砷化铟)衬底上生长的InAs0.05Sb0.95(铟砷锑)厚膜单晶,制作了高灵敏度、非制冷型、中长波光导型探测器,探测器上安装了Ge(锗)浸没透镜。傅里叶变换红外(FTIR)吸收光谱显示InAsSb材料的本征吸收边出现在波长8μm以后。InAs0.05Sb0.95探测器的光谱响应波长范围为2~9μm。室温下,在波长6.5μm处的峰值探测率Dλp*达到5.4×109 cm·Hz1/2·W-1,在波长8.0μm和9.0μm处的探测率D*分别为9.3×108和1.3×108 cm·Hz1/2·W-1,显示了InAsSb探测器的优越性能及对红外探测和成像的应用前景。     

Enhanced photoresponse and photocatalytic activities of graphene quantum dots sensitized Ag/TiO2 thin film

TiO₂ thin films were fabricated through hydrothermal method. Silver nanoparticles were loaded on TiO₂ thin films via photoreduction technique. Subsequently, the graphene quantum dots (GQDs) were spin‐coated on the Ag/TiO₂ nanocomposites thin films. The crystal structure, surface morphology and UV‐vis absorbance were tested by XRD, SEM and ultraviolet‐visible spectrophotometer. These results indicated that Ag nanoparticles and GQDs are anchored on the TiO₂ nanorods. Absorbance of Ag/TiO₂ and GQDs/Ag/TiO₂ nanocomposite thin films have been extended into the visible region. Visible‐light response of the samples were investigated by electrochemical workstation. The photoresponse of the sample can be enhanced by sensitization of the Ag nanoparticles and GQDs. The enhanced visible‐light response may be due to the surface plasmon resonance of silver nanoparticles and visible absorbance of GQDs. The highest photocatalytic activity has been observed in the 9‐GQDs/Ag/TiO₂ composite thin film. The efficient charge separation and transportation can be achieved by introducing the Ag nanoparticles and GQDs in the TiO₂ thin film.     

脉冲激光沉积法制备的单层MoS2薄膜变温光响应研究

报导了在c-Al₂O₃衬底上用脉冲激光沉积法制备MoS₂薄膜,并测试了其不同温度下的光响应。通过拉曼散射光谱和X射线衍射光谱证明了所制备的二硫化钼为纯2H相。通过X光电子能谱证明了所制备的二硫化钼硫钼原子比为1.92：1,在Mo元素的3d核心能级谱中存在红移和蓝移,说明薄膜中存在氧化和硫缺陷。此外,通过拉曼和光致发光分布图,证明了薄膜具有良好的均一性。在不同层数的二硫化钼样品中,单层二硫化钼样品具有最强的光响应,达到3 mAW^-1。单层二硫化钼的变温光响应实验表明,在室温附近,温度升高会提高二硫化钼的光响应强度和响应时间。