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Barrier engineering for HgCdTe unipolar detectors on alternative substrates
摘要： Delta-doped layers together with compositionally grading have been utilized to get nBn configurations for the HgCdTe material system in all the short-wave (SWIR), medium-wave (MWIR) and long-wave (LWIR) infrared bands. Shockley Read Hall (SRH), trap-assisted tunneling (TAT), Auger and radiative recombination mechanisms have been included in the analyses and strong suppression of SRH and TAT currents have been demonstrated with the designed structures. This methodology is especially useful when the carrier lifetime is limited due to alternative substrate usage. No degradation in photo-response has been observed as adjusting the valence band offset is quite flexible with the delta-doped nano-layers and the valence band barrier can be completely removed. Calculations have been performed for 1–3 μs lifetime targeting the alternative substrate applications and up to 60 degrees of increase in the operation has been shown to be possible.
关键词： HgCdTe,nBn,Photodetector,Barrier structures
更新于2025-09-23 15:23:52
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Electrical profiling of arsenic-implanted HgCdTe films performed with discrete mobility spectrum analysis
摘要： Results of electrical profiling of an n-on-p junction formed by 190-keV arsenic ion implantation in indium/vacancy–doped Hg0.78Cd0.22Te film are presented. Mobility spectrum analysis in combination with wet chemical etching has been employed for the profiling. After the implantation, a typical n+-n–p structure was observed and three electron species were detected: (a) low-mobility electrons in the 400-500 nm-thick top radiation-damaged n+-layer, (b) mid-mobility electrons also originating from radiation damage and spreading down to 700-900 nm, and (c) high-mobility electrons located in the n-region extending beyond 700-900 nm and down to the p-n junction. A comparison of the extracted electron parameters with the arsenic profile obtained with secondary-ion mass spectroscopy as well as with the defect pattern obtained with transmission electron microscopy allowed for identification of the origin of all the three electron species.
关键词： HgCdTe,arsenic implantation,defects,electrical profiling
更新于2025-09-23 15:23:52
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Nano-size defect layers in arsenic-implanted and annealed HgCdTe epitaxial films studied with transmission electron microscopy
摘要： Optical reflectance and bright-field and high-resolution transmission electron microscopy studies of radiation damage induced by implantation of arsenic ions with 190 keV and 350 keV energy and 1014 cm–2 fluence in molecular-beam epitaxy-grown Hg0.7Cd0.3Te films were performed. A similarity in defect pattern formed by arsenic implantation in Hg1?xCdxTe with x ≈ 0.2 and x ≈ 0.3 straight after the implantation was observed with formation of three nano-size defect layers containing dislocation loops of vacancy- and interstitial-types, single dislocations and lattice deformations. After post-implantation arsenic activation annealing, most of these defects in our Hg0.7Cd0.3Te films, in contrast to Hg0.8Cd0.2Te films, disappeared. This effect is explained by the reduced influence of the electric field of the graded-gap surface layer on the diffusion of charged point defects under annealing.
关键词： HgCdTe,Transmission electron microscopy,Defects,Arsenic implantation
更新于2025-09-23 15:19:57
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A Preamplifier for a CdHgTe Photodetector
摘要： A preamplifier for operation with an HgCdTe-based nitrogen-cooled IR photodetector (600 nm–15 μ m) is described. The preamplifier operates in the photoconductivity mode. The use of modern microcircuits made it possible to increase the bandwidth of the response to 2 MHz at a noise level of 0.5 nV/Hz1/2, which is close to the fundamental limit that is specified by the resistance of the photosensitive element. The preamplifier was used in an aperture-free scanning near-field optical microscope.
关键词： HgCdTe,IR photodetector,scanning near-field optical microscope,photoconductivity,preamplifier
更新于2025-09-23 15:19:57
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HgCdTe Quantum Dot Over Interdigitated Electrode for Mid-Wave Infrared Photon Detection and Its Noise Characterization
摘要： In this paper, we report the development of mid-wave infrared (MWIR) photon sensor using solution-processed mercury cadmium telluride (Hg1(cid:1)xCdxTe) semiconductor colloidal quantum dots (CQDs) coated over interdigitated metallic electrode structure, having signiˉcant response in the MWIR spectral band range ((cid:1) ? 2:5–5.0 (cid:3)m) at room temperature. HgCdTe CQD has been chemically synthesized. We have characterized the optical and 1=f noise performances of the developed sensor to understand its behaviors at di?erent operating biases as an introductory step toward development of large-format MWIR focal-plane arrays having similar pixel structure. The optimum biasing conditions have been experimentally evaluated at room temperature. We have achieved a noise equivalent power (NEP) of 2.5 pW at 1.5-V bias voltage which corresponds to detectivity (D(cid:3)) in the order of 108. This work highlights the development of low-cost colloidal HgCdTe quantum dot photodetectors and their utility in the monolithic infrared focal-plane arrays.
关键词： MWIR,CQD,FPA,1/f noise,HgCdTe
更新于2025-09-23 15:19:57
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Type-II superlattice photodetectors versus HgCdTe photodiodes
摘要： The development of the HgCdTe alloy as the most important intrinsic semiconductor for infrared (IR) technology is well established and recognized. In spite of the achievements in material and device quality, the drawbacks still exist due to bulk and surface instability, lower yields and higher costs particularly in fabrication of long wavelength infrared arrays. The dif?culties with this material encouraged to research on other compounds to improve device performance. Since the ?rst paper published by Sakaki and Esaki in 1978 it is well known that InAs and GaSb constitute a nearly lattice-matched material system offering great ?exibility in the design of IR optoelectronic devices. After four decades, the III-V type-II superlattice (T2SL) detector technology is under strong development as a possible alternative to HgCdTe. The novel ideas coming in design of detectors have enhanced the position of T2SLs in IR materials detector technology. It appears that T2SLs are especially helpful in the design of unipolar barriers. In this paper fundamental physical properties of two material systems, HgCdTe and T2SLs, are compared together with their in?uence on detector performance: dark current density, RA product, quantum ef?ciency, and noise equivalent different temperature. In comparison with HgCdTe, fundamental properties of T2SLs are inferior. On the other hand, T2SL and barrier detectors have several advantages to include lower tunnelling and surface leakage currents, and suppressed Auger recombination mechanism. Up to date, the promise of superior performance of these detectors has not been realized yet. In the paper we present that the performance of T2SL detectors (dark current, current responsivity, and noise equivalent difference temperature) is lower than bulk HgCdTe photodiodes. Due to stronger, less ionic chemical bonding of III-V semiconductors, these materials are attractive due to manufacturability and stability. It is also predicted that the interband T2SL quantum cascade devices will outperform the performance of the high operating temperature HgCdTe detectors.
关键词： Type-II superlattices,Responsivity,HgCdTe,Operability,Dark current,Interband cascade infrared detectors,Carrier lifetime
更新于2025-09-16 10:30:52
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Uncooled Mid-wave Infrared Focal Plane Array Using Band Gap Engineered Mercury Cadmium Telluride Quantum Dot Coated Silicon ROIC
摘要： The dominant photon detectors and focal plane arrays (FPAs) in the mid-wave infrared (MWIR) range (λ = 3 μm to 5 μm) use single crystal InSb and HgCdTe materials. The cost of these detectors is high, and cooling at approximately 80 K to 120 K is required to reduce the dark current. Colloidal quantum dots (CQDs) can be used to provide the speed and detectivity (D*) of the quantum detectors with lower fabrication costs than those of single crystal epitaxial materials. The aim of this study is to develop a MWIR area array sensor with an HgCdTe-ternary alloyed semiconductor CQD using a commercially available silicon readout integrated circuit (ROIC). First, we synthesized a solution processed HgCdTe CQD responsive in the MWIR range at room temperature and developed a Schottkey junction photodiode array of 10 × 10 pixels based on the same quantum dots (QDs) to produce a HgCdTe-Si interface suitable for a MWIR photodiode at room temperature. After ensuring its functionality, we developed a 320 × 256-pixel focal plane array (FPA) responsive in the MWIR region by hybridization of the HgCdTe CQD layer over a silicon ROIC die with a direct injection input circuit. The FPA was operated using an indigenously developed Field Programmable Gate Array (FPGA)-based drive unit, and different IR targets were imaged to evaluate its use as a low-cost MWIR FPA. NEΔT value of 4 K achieved at room temperature.
关键词： FPA,MWIR,CQD,NEΔT,HgCdTe
更新于2025-09-12 10:27:22
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A Megapixel Matrix Photodetector of the Middle Infrared Range
摘要： The characteristics of MWIRs focal plane aeeays made in the form of a hybrid chip based on a planar n+–p-HgCdTe focal matrix with 2048 × 2048 elements and a silicon multiplexer are considered. The temperature dependence of the reverse current of elements in the 125–300 K range had a characteristic Arrhenius dependence with an activation energy close to the band gap of the semiconductor and was limited by the diffusion component of the current. At a lower temperature, the current was limited by the generation of carriers with the participation of a deep level near the middle of the forbidden band. The histogram of the detectability of the elements of the matrix had the form of a symmetric curve with a maximum and an average value ≈ 1.3 × 1012 cm Hz1/2/W.
关键词： FPA,heterostructure,multiplexer,detectability,HgCdTe,IR matrix
更新于2025-09-12 10:27:22
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Analysis of dark current generated by long-wave infrared HgCdTe photodiodes with different implantation shapes
摘要： Resistance-voltage curves of B+-implanted n-on-p Hg1-xCdxTe long-wavelength infrared photodiodes with different implantation unit shapes were measured for temperatures in the 20–140 K range. The response spectrum of the device was measured, and the response cutoff wavelength was 11.45 μm. By fitting the experimental data, R0A at different temperatures and the dark current at different bias voltages of the two long-wavelength diodes were calculated theoretically. The results demonstrate that the response spectrum of the device is affected by the implantation shape. The temperature transformation point of the dominant dark current was 40 K, and correlations between some parameters were also demonstrated.
关键词： dark current,long-wave infrared,HgCdTe,photosensors
更新于2025-09-11 14:15:04
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Large spin-orbit splitting in inversion layers on HgCdTe with an inverted band structure
摘要： This paper reports the study of the magneto-transport properties of a two-dimensional electron gas confined in inversion layers on HgCdTe with an inverted band structure. The magnetoresistance exhibits Shubnikov-de Hass oscillations, where beating patterns are observed at low magnetic field. This can be attributed to the zero-field spin splitting. By using the fast Fourier transformation of the observed beating patterns, the zero-field spin splitting energy is extracted. The extracted energy up to ～ 34 meV is obtained, which is far larger than that in inversion layers on HgCdTe with a normal band structure. This offers a route to realize a HgTe-based spintronic device that works at room temperature.
关键词： spin-orbit splitting,spintronic device,inversion layers,HgCdTe
更新于2025-09-09 09:28:46