基于VO2薄膜非致冷红外探测器光电响应研究

VO₂薄膜是非致冷微测辐射热红外探测器热敏电阻材料.研究中应用微电子工艺制备了VO₂溅射薄膜红外探测器,在296K的环境中测试了该探测器在不同的直流偏置、光调制频率下对873K标准黑体源8—12μm红外辐射的光电响应以及器件的噪声电压,在10和30Hz的调制频率下其响应率分别大于17kV/W和接近10kV/W.该探测器实现了探测率D大于1.0×10⁸cm (Hz)^1/2/W,热时间常量为0.011s的8—12μm非致冷 关键词： 非致冷测辐射热探测器 红外探测器 二氧化钒 薄膜     

Thermo-electric charge-to-voltage converter with superconductor–insulator–normal tunnel junction for bolometer applications

A novel type of the zero-biased thermo-electric bolometer (TEB) is proposed. The bolometer is based on a charge-to-voltage converter (CVC) with a superconductor–insulator–normal (SIN) tunnel junction and a superconducting absorber. The absorption of photons in the absorber leads to excitation of quasiparticles with some fraction of charge imbalance, tunneling through the SIN junction in zero-biased mode and generation of voltage. The thermoelectric voltage is determined by accumulation of tunneling charge in an external capacitance. Conversion efficiency is very high and voltage values comparable with a superconducting gap are easily achieved. The zero-biased CVC–TEB can be effectively used for creation of an array of bolometers and multi-pixel detection systems.     

Microwave Transmission Technique for Accurate Impedance Characterization of Superconductive Bolometric Mixers

The impedance of the submillimeter superconducting hot-electron bolometer mixer was measured in the range 0.2-4 GHz. A special technique relying on determination of the S ₂₁ transmission parameter of the device was used. Many advantages of the technique (wide frequency range, in situ calibration, low test power, accuracy) are demonstrated. The estimate of the mixer bandwidth from the impedance data using the mixer theory is in good agreement with the results of the direct bandwidth measurements.     

Exploratory growth in the Li2MoO4-MoO3 system for the next crystal generation of heat-scintillation cryogenic bolometers

In this work, we report on the Czochralski growth of Li₂MoO₄ crystals up to 230 g for heat-scintillation cryogenic bolometers likely to be used in astroparticle physics and neutron spectroscopy. Their transmission properties, radiopurity levels and detector behavior characterizations were carried out in order to validate the crystal growth process. The melting characteristics, the partition coefficients of a broad range of impurities, the thermal expansion (lattice parameters and dilatometry) and specific heat properties of the crystals were measured, over a broad temperature range for the last two, providing new data likely to be used in crystal growth process numerical simulations. We also investigated the crystal growth of Li₄Mo₅O₁₇ and determined its melting behavior and specific heat. The physical properties directly relevant to heat-scintillation cryogenic bolometers of Li₂MoO₄ and Li₄Mo₅O₁₇ are discussed in the context of the current materials developed for such applications.     

微波与热偏置下超导HEB太赫兹直接检测器的性能比较

本文介绍了一种基于超导氮化铌(NbN)热电子测辐射热计(HEB)的太赫兹(THz)直接检测器,并利用直流读出法和微波反射读出法,对微波与热偏置下HEB直接检测器的性能进行了比较.通过直流读出法,在最佳工作点处,测得微波偏置与热偏置条件下检测器的电流响应率分别为244A/W和20A/W,光学噪声等效功率(NEP)分别为4.5pW/√Hz和6.8pW/√Hz.相比于热偏置,微波偏置能够大大提高检测器的响应率.此外,我们利用微波反射读出法对微波偏置和热偏置下检测器的性能进行了比较.两种读出方式均可很好的表征检测器的性能,而相比于直流读出法,微波反射读出法更易于扩展到多像素阵列,同时具有很快的读出速度,对快速THz脉冲信号的检测具有重要意义.     

A concept for a tunable antenna-coupled intersubband terahertz (TACIT) detector

Detectors based on intersubband transitions in quantum wells have great potential for use between one and several terahertz. We propose a tunable, antenna-coupled, intersubband terahertz (TACIT) detector that is both sensitive and fast, with a speed limited only by the intersubband relaxation rate (1 ns at at ). The detector is sensitive over a narrow range of frequencies, and the frequency of peak absorption can be tuned by applying a bias voltage to the device.     

Ambient temperature or moderately cooled semiconductor hot electron bolometer for mm and sub-mm regions

A model of semiconductor hot electron bolometer (SHEB), in which electromagnetic radiation heats only electrons in narrow-gap semiconductor without its lattice slow-response heating, is considered. Free carrier heating changes the generation-recombination processes that are the reason of semiconductor resistance rise. It is estimated, that Hg_0.8Cd_0.2Te detector noise equivalent power (NEP) for mm and sub-mm radiation wavelength range can reach NEP ∼10⁻¹¹ W at Δf = 1 Hz signal gain frequency bandwidth. Measurements performed at electromagnetic wave frequencies v = 36, 39, 55, 75 GHz, and at 0.89 and 1.58 THz too, with non-optimized Hg_0.8Cd_0.2Te antenna-coupled bolometer prototype confirmed the basic concept of SHEB. The experimental sensitivity S_v ∼2 V/W at T = 300 K and the calculated both Johnson-Nyquist and generation-recombination noise values gave estimation of SHEB NEP ∼3.5 × 10⁻¹⁰ W at the band-width Δf = 1 Hz and v = 36 GHz.     

Samuel Pierpont Langley and his Contributions to the Empirical Basis of Black-Body Radiation

In this paper I deal with an early phase of the history of research on black-body radiation. In this phase, from 1880-1900, the American astrophysicist Samuel Pierpont Langley (1834-1906) invented and used a key instrument, the bolometer, to measure for the first time radiation curves that displayed the characteristic features of asymmetry and of a shifting of their maxima to shorter wavelengths with increasing temperature. I emphasize the complex development of the construction of the bolometer and the early experiments performed with it. I also discuss how these developments became important for theoretical research on the black-body radiation formula. My aim is to show that the often-neglected experimental part of the history of research on black-body radiation represents an important precondition for the theoretical developments that followed.     

两种Z箍缩X射线总能量测量技术对比

薄膜量热计和闪烁探测系统是国内常用于Z箍缩辐射总能量测量的两种诊断手段。两种方法基于完全不同的诊断原理,通过对比其诊断结果可以提高Z箍缩X射线总能量测量的精度,加深对Z箍缩的理解。采用上述两种诊断装置对“强光一号”加速器Z箍缩实验中多种材料和构型的负载辐射总能量进行了测量。结果表明,对于Al丝阵负载,无论是单排还是双排平面丝阵,随着负载参数的变化,两种手段总能量测量结果均发生改变且呈正比,二者符合较好;但对于镀膜W丝阵两种方法的诊断结果差异较为明显,随着丝间距的增大,量热计测量结果明显减小,但闪烁探测系统的测量结果却变化较小,二者不再呈比例关系。通过模拟计算对产生上述现象的原因进行了分析,可以得出如下结论：(1)闪烁探测系统对低能光子响应较高,且响应能谱范围较量热计宽,因此所有的总能量测量结果比量热计测量结果略大;(2)Al丝阵等离子体辐射能谱分布范围较宽,主要辐射能段处于两种测量手段响应都比较平坦的区间内,因此两种手段测量结果符合较好;(3)W丝阵辐射主要集中在1 keV以下的软X射线能段,处于镍薄膜全吸收范围内,因此量热计测量结果应该是比较准确的;(4)对于闪烁探测系统测量结果对镀膜W丝阵负载参数不敏感的现象,一种可能的解释是：随着W丝阵丝间距增大,等离子体滞止时刻的温度减低,导致能谱软化,但辐射谱型向闪烁体灵敏度较高的方向移动。因此虽然总能量降低了,但闪烁探测系统的测量结果变化却不大;(5)辐射中电子的影响同样不可忽视。     

Bolometric effect in a waveguide-integrated graphene photodetector

Graphene is an alternative material for photodetectors owing to its unique properties.These include its uniform absorption of light from ultraviolet to infrared and its ultrahigh mobility for both electrons and holes.Unfortunately,due to the low absorption of light,the photoresponsivity of graphene-based photodetectors is usually low,only a few milliamps per watt.In this letter,we fabricate a waveguide-integrated graphene photodetector.A photoresponsivity exceeding0.11 A·W ~(-1) is obtained which enables most optoelectronic applications.The dominating mechanism of photoresponse is investigated and is attributed to the photo-induced bolometric effect.Theoretical calculation shows that the bolometric photoresponsivity is 4.6 A·W ~(-1).The absorption coefficient of the device is estimated to be 0.27 dB·μm ~(-1).