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1.
Optimization of a solar-blind and middle infrared two-colour photodetector using GaN-based bulk material and quantum wells 下载免费PDF全文
This paper calculates the wavelengths of the interband
transitions as a function of the Al mole fraction of AlxGa1-xN bulk material. It is finds that when the Al mole fraction is
between 0.456 and 0.639, the wavelengths correspond to the solar-blind
(250~nm to 280~nm). The influence of the structure parameters of
AlyGa1-yN/GaN quantum wells on the wavelength and absorption
coefficient of intersubband transitions has been investigated by
solving the Schr?dinger and Poisson equations self-consistently. The
Al mole fraction of the AlyGa1-yN barrier changes from
0.30 to 0.46, meanwhile the width of the well changes from 2.9~nm to
2.2~nm, for maximal intersubband absorption in the window of the air
(3~μm <λ <5~μm). The absorption coefficient of the
intersubband transition between the ground state and the first
excited state decreases with the increase of the wavelength. The
results are finally used to discuss the prospects of GaN-based bulk
material and quantum wells for a solar-blind and middle infrared
two-colour photodetector. 相似文献
2.
采用有效质量模型下的4×4 Luttinger-Kohn哈密顿量矩阵对In0.53Ga0.39Al0.08As/InxGa1-xAs0.9Sb0.1量子阱结构的能带进行了计算。求得了C1-HH1跃迁波长随In组分及阱宽的变化关系,并采用力学平衡模型计算了此应变材料体系在生长时的临界厚度。结果表明,在结构设计和材料生长中采用合适的材料组分和阱宽,在InP基InGaAlAs/InGaAsSb应变量子阱激光器中能够实现1.6~2.5 μm近中红外波段的激射波长。 相似文献
3.
N. Li D.-Y. Xiong X.-F. Yang W. Lu W.-L. Xu C.-L. Yang Y. Hou Y. Fu 《Applied Physics A: Materials Science & Processing》2007,89(3):701-705
We study the dark current of the GaAs/AlGaAs quantum-well infrared photodetector (QWIP) by assuming a drift-diffusion carrier transport in the barriers where the electric fields are obtained by the current continuity condition and the self-consistent energy band structure. It has been shown that due to the current continuity condition, the dark currents across the QWIP devices are determined by the thermionic emission from the emitter to the multiple quantum well (MQW) region. The self-consistent calculation of the Schrödinger and Poisson equations shows a weak electric field in the barrier region connecting to the emitter (much smaller than the average field across the QWIP at low bias) due to the accumulation of carriers in the triangle quantum well formed at the emitter-MQW interface, which results in a very small dark current at low bias. The numerical results explain well our experimental observation. 相似文献
4.
半导体量子点具有独特的光学与电学性质,特别是红外量子点良好的光稳定性和生物相容性等优点使其在光电器件、生物医学等领域受到广泛关注。综述了吸收或发射光谱位于红外波段的量子点在激光、能源、光电探测以及生物医学等方面的应用现状与前景,归纳了适用于红外量子点材料的制备方法,并对比了不同方法在应用中的优势。半导体红外量子点材料选择丰富、应用形式多样:InAs量子点被动锁模激光器在1.3 μm波长处产生7.3 GHz的近衍射极限脉冲输出;InAs/GaAs量子点双波长激光器可泵浦产生0.6 nW的THz波;PbS量子点掺杂光纤放大器可在1.53 μm中心波长处实现10.5 dB光增益,带宽160 nm;CdSeTe量子点敏化太阳能电池、异质结Si基量子点太阳能电池的总转换效率可达8%和14.8%;胶质HgTe量子点制成的量子点红外探测器(QDIP)可实现3 μm~5 μm中波红外探测,Ge/Si量子点可实现3 μm~7 μm红外探测;CdTe/ZnSe核壳量子点可用于检测DNA序列的损伤与突变。半导体红外量子点上述应用形式的发展,将进一步促进红外光电系统向高效、快速、大规模集成的方向演进,也将极大地促进临床医学中活体成像检测的应用推广。 相似文献
5.
6.
D.Z.-Y. Ting Y.-C. Chang S.V. Bandara C.J. Hill S.D. Gunapala 《Infrared Physics & Technology》2007,50(2-3):136-141
We examined theoretically band structure and discrete dopant effects in the quantum well infrared photodetector (QWIP) and the quantum dot infrared photodetector (QDIP). We find that in QWIPs discrete dopant effects can induce long wavelength infrared absorption through impurity assisted intra-subband optical transitions. In QDIPs, we find that a strategically placed dopant atom in a quantum dot can easily destroy the symmetry and modify the selection rule. This mechanism could be partially responsible for normal incidence absorption observed in low-aspect-ratio quantum dots. 相似文献
7.
The paper reports on the barrier mid-wave infrared InAs/InAsSb (xSb = 0.4) type-II superlattice detector operating below thermoelectrical cooling. AlAsSb with Sb composition, xSb = 0.97; barrier doping, ND < 2×1016 cm?3 leading to valence band offset below 100 meV in relation to the active layer doping, ND = 5×1015 cm?3 was proved to be proper material not introducing extra barrier in valence band in the analyzed temperature range in XBn architectures. The detectivity of the simulated structure was assessed at the level of ~ 1011 Jones at T ~ 100 K assuming absorber thickness, d = 3 μm. The detector’s architecture for high frequency response operation, τs = 420 ps (T ~ 77 K) was presented with a reduced active layer of d = 1 μm. 相似文献
8.
J. H. Lu Y. Y. Yang C. C. Chen C. H. Kuan H. T. Chen S. C. Lee 《Infrared Physics & Technology》2003,44(5-6):399-409
Superlattices have been demonstrated previously by our group in the design of the multicolor infrared photodetector. In general, the period number of the superlattice may be up to several dozens. In this paper, we have investigated the performance of the infrared photodetectors especially with 3, 5 and 15 periods. The detector structure contains a thick blocking barrier embedded between two superlattices with different period numbers but with the same well and barrier widths. This double-superlattice structure shows switchable spectral responses between two spectral regions by the voltage polarities. The photoresponse in each spectral region is also tunable by the magnitude of the applied voltage. The voltage-dependent behavior reveals the photoelectron relaxation and transport mechanism in the superlattice miniband. Superlattice with few periods has high electron group velocity, less relaxation effect and less collection efficiency. Therefore the superlattice with few periods may have better responsivity and narrower photoresponse range than the one with many periods. Based on the experimental results of our devices, it is observed that the superlattice with fewer periods has better detectivity, responsivity, wider range of the operational temperature, and more flexible miniband engineering than the conventional multiple quantum well infrared photodetector. 相似文献
9.
为了获取足够的目标信息,充分利用中波红外和长波红外的光谱信息,建立了谐衍射中、长波红外超光谱成像系统.利用谐衍射元件独特的色散特性,将谐衍射透镜应用于中、长波红外超光谱成像系统中,使系统在中波红外3.7—4.8 μm和长波红外8—12 μm的2个红外大气窗口内获取数百个光谱图像.设计结果表明,中波红外波段,在18对线/mm处光学系统的调制传递函数(MTF)大于0.55,长波红外波段,在13对线/mm处光学系统的MTF大于0.5,光学系统的衍射环绕能,在中波红外波段30 μm半径范围内大于85%,在长波红外 相似文献
10.
A. G. U. Perera 《Opto-Electronics Review》2006,14(2):99-108
The work describes multiband photon detectors based on semiconductor micro-and nano-structures. The devices considered include
quantum dot, homojunction, and heterojunction structures. In the quantum dot structures, transitions are from one state to
another, while free carrier absorption and internal photoemission play the dominant role in homo or heterojunction detectors.
Quantum dots-in-a-well (DWELL) detectors can tailor the response wavelength by varying the size of the well. A tunnelling
quantum dot infrared photodetector (T-QDIP) could operate at room temperature by blocking the dark current except in the case
of resonance. Photoexcited carriers are selectively collected from InGaAs quantum dots by resonant tunnelling, while the dark
current is blocked by AlGaAs/InGaAs tunnelling barriers placed in the structure. A two-colour infrared detector with photoresponse
peaks at ∼6 and ∼17 μm at room temperature will be discussed. A homojunction or heterojunction interfacial workfunction internal
photoemission (HIWIP or HEIWIP) infrared detector, formed by a doped emitter layer, and an intrinsic layer acting as the barrier
followed by another highly doped contact layer, can detect near infrared (NIR) photons due to interband transitions and mid/far
infrared (MIR/FIR) radiation due to intraband transitions. The threshold wavelength of the interband response depends on the
band gap of the barrier material, and the MIR/FIR response due to intraband transitions can be tailored by adjusting the band
offset between the emitter and the barrier. GaAs/AlGaAs will provide NIR and MIR/FIR dual band response, and with GaN/AlGaN
structures the detection capability can be extended into the ultraviolet region. These detectors are useful in numerous applications
such as environmental monitoring, medical diagnosis, battlefield-imaging, space astronomy applications, mine detection, and
remote-sensing.
The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 59570W (2005). 相似文献
11.
GaAs/AlGaAs超晶格的光致发光 总被引:1,自引:0,他引:1
在室温下测量了GaAs/A l0.3Ga0.7As超晶格的光致发光,发现在波长λ=761 nm处存在一较强的发光光峰,此发光峰目前尚未见报道。经理论分析表明,此峰是量子阱中的第一激发态电子与受主空穴复合发光。实验还观测到在λ=786 nm处,λ=798 nm处和λ=824 nm处分别存在一发光峰,分析表明λ=786 nm处的发光峰为量子阱阱中费米能级附近的电子与轻空穴复合发光;λ=798 nm处的发光峰为量子阱内的基态电子到轻空穴的复合发光;λ=824 nm处的发光峰为阱中激子复合复合发光。理论计算与实验结果符合的很好。 相似文献
12.
本文报道了采用分子束外延技术制备的三色InAs/GaAs量子点红外探测器. 器件采用nin型结构, 吸收区结构是在InGaAs量子阱中生长含有AlGaAs插入层的InAs量子点, 器件在77 K下的红外光电流谱有三个峰值: 6.3, 10.2和11 μm. 文中分析了它们的跃迁机制, 并且分别进行了指认. 因为有源区采用了不对称结构, 所以器件在外加偏压正负方向不同时, 光电流谱峰值的强度存在一些差异. 不论在正偏压或者负偏压下, 当偏压达到较高值, 再进一步增大偏压时, 都出现了对应于连续态的跃迁峰强度明显下降的现象, 这是由量子点基态与阱外连续态的波函数交叠随着偏压进一步增大而迅速减小导致的. 相似文献
13.
Lioutas ChB Zoulis G Konidaris S Polychroniadis EK Stróz D 《Micron (Oxford, England : 1993)》2009,40(1):6-10
GaSb is a promising III-V direct band gap semiconductor with sphalerite type FCC structure. Its band gap value has made it an excellent candidate for the conversion of infrared radiation to electricity. The wafers of GaSb, that were studied, originated from ingots grown with the Liquid Encapsulated Chochralski method. In all cases, Energy Dispersive X-ray Spectroscopy and Particle Induced X-ray Emission measurements demonstrated an excess of Sb. In the present work conventional transmission electron microscopy (CTEM) and high resolution electron microscopy (HRTEM) were used in order to determine the effect of the Sb excess in the structural characteristics of the material, mainly after thermal treatment. A structure model based on the ordering of the Sb antisites (Sb(Ga)) rather than the Ga vacancies (V(Ga)) is proposed for the observed modulation in small areas of the material. 相似文献
14.
15.
Y. Fu M. Willander D.K. Sengupta 《Applied Physics A: Materials Science & Processing》2005,80(3):523-528
p- and n-type InxGa1-xAs-InP quantum wells are suitable for multi-color infrared photodetector applications in atmospheric windows due to improved barrier quality and carrier-transport properties. We apply the k
·p
method to study the energy band structures and optical transition properties, which show that the peak response wavelengths of p- and n-type InxGa1-xAs-InP quantum well infrared photodetectors (QWIPs) are determined not only by the energy distance from the ground sublevels in the quantum well to the energy band edges of extended states, but also by the characteristics of the extended states. The optical phonon scattering process converts the broad absorption spectrum of the p-QWIP from 0 to 16 m into a short-wavelength spectrum centered at 4.5 m. The transport of electrons in the extended states of the n-QWIP is characterized by running wave boundary conditions, resulting in a theoretically optimal absorption rate by a 8-nm-thick In0.53Ga0.47As quantum well. Moreover, a conduction-band offset of 0.5 for an InxGa1-xAs-InP (x=0.53) heterostructure gives the best data fitting of theoretical and experimental response peaks, whereas 0.55 is generally recommended in the literature. PACS 73.21.-b; 73.63.Hs; 78.67.-n 相似文献
16.
用传统熔融淬冷法制备了新型远红外Te基硫系玻璃(100-x)(GeTe4)-xGa (x=0, 5, 10 mol%).利用差热分析(DTA)、可见/近红外吸收光谱、红外透射光谱等技术,在GeTe4玻璃的基础上,通过引入较高配位金属Ga, 研究其对玻璃组成、结构和性能的影响,利用经典的Tauc方程计算了样品光学带隙允许的直接跃迁、允许的间接跃迁及Urbach能量.分析结果表明:在GeTe4玻璃中引入
关键词:
光学材料
硫系玻璃
光学带隙
红外光谱 相似文献
17.
Antimony-based materials continue to provide great interest for infrared photodetector and focal plane array imaging applications. Detector architectures include InAs/Ga(In)Sb strained-layer superlattices, which create a type-II band alignment that can be tailored to cover a wide range of the mid- and long-wavelength bands by varying the thickness and composition of the constituent materials, and bulk InAsSb-based XBn barrier designs. These materials can provide desirable detector features such as wider wavelength range, suppression of tunneling currents, improved quantum efficiency, and higher operating temperatures. In order to bring these advantages to market, a reliable manufacturing process must be established on large diameter substrates. We report our latest work on the molecular beam epitaxy growth of Sb-detector epiwafers on 100 mm diameter GaSb substrates in a multi-wafer production format. The growth process has been established to address the challenges of these demanding structures, including the large numbers of alternating thin layers and mixed group-V elements. Various characterization techniques demonstrate excellent surface morphology, crystalline structure quality, and optical properties of the epiwafers. The measured wafer-to-wafer consistency and cross-wafer uniformity demonstrate the potential for volume manufacturing. 相似文献
18.
David Z.-Y. Ting Sumith V. Bandara Jason Mumolo Sam A. Keo Jean Nguyen H.C. Liu C.Y. Song Yia-Chung Chang Sir B. Rafol Cory J. Hill Sarath D. Gunapala Alexander Soibel John K. Liu Edward Blazejewski 《Infrared Physics & Technology》2009,52(6):294-298
We report work on several quantum structure based infrared detectors. We describe the concept of the submonolayer quantum dot based infrared photodetectors, report device results, and present imaging results from a megapixel focal plane array. We describe the concept and experimental progress of the quantum well intra-subband photodetector (QWISP), which is closely related to the quantum well infrared photodetector (QWIP), but uses the dopant-assisted intra-subband absorption mechanism in quantum wells for normal-incidence far infrared/terahertz radiation detection. We discuss aspects of superlattice heterostructure based barrier infrared detectors (BIRDs). 相似文献
19.
M. Hostut M. Alyoruk Y. Ergun I. Sokmen 《Applied Physics A: Materials Science & Processing》2010,98(2):269-273
A theoretical investigation of a GaAs/AlGaAs-material-system-based four quantum well infrared detector structures consisting
of ten periods of three asymmetric quantum well units are presented. Each quantum well in the units is sensitive to wavelengths
of 8.75, 10, and 11.75 μm, respectively. The effect of the barrier thicknesses on the responsivity spectra is discussed with
respect to barrier transmissions under negative and positive bias voltages. Each detector structure shows voltage-tunable
broadband and multicolor features in 8–12-μm long wavelength infrared range (LWIR). 相似文献
20.
A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology. 相似文献