High absorption (&amp;gt;90%) quantum-well infrared photodetectors

Liu, H. C.; Dudek, R.; Shen, Aidong; Dupont, Emmanuel; Song, Chunying; Wasilewski, Z. R.; Buchanan, M.

doi:10.1063/1.1425066

Cited by 67 publications

(39 citation statements)

References 6 publications

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“…This has been proven by different types of quantum well infrared photodetectors ͑QWIPs͒ which work in a variety of different wavelength ranges. 11,12 By further exploiting the concept of using QCL-like structures as detectors, 13 we present here a THz detector based on a GaAs/AlGaAs based superlattice structure. The advantage of this approach is that electrons will be trapped in the subsequent active well as soon as they have made their contribution to the photocurrent; resulting in a good noise behavior.…”

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confidence: 99%

Terahertz range quantum well infrared photodetector

Graf¹,

Scalari²,

Hofstetter³

et al. 2004

Applied Physics Letters

199

119

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We demonstrated a GaAs/AlGaAs-based far-infrared quantum well infrared photodetector at a wavelength of ϭ84 m. The relevant intersubband transition is slightly diagonal with a dipole matrix element of 3.0 nm. At 10 K, a responsivity of 8.6 mA/W and a detectivity of 5ϫ10 7 cm ͱHz/W have been achieved; and successful detection up to a device temperature of 50 K has been observed. Being designed for zero bias operation, this device profits from a relatively low dark current and a good noise behavior.In recent years, there has been an increasing interest in the fabrication of so-called terahertz ͑THz͒ emitters and detectors. While electronic devices like Gunn diodes or Schottky diode frequency multipliers try to reach this range from the low frequency end, optical devices like gas or semiconductor lasers are quickly moving into the THz range from the high frequency side. [1][2][3] Since the THz region is traditionally defined as 0.1-3 THz, the currently available quantum cascade laser ͑QCL͒ sources with ϭ87 m can already be regarded as THz sources. At low temperatures, they emit several milliwatts of continuous wave output power. On the electronics side, Gunn diodes and frequency mixers have also achieved several milliwatts of radiated power at frequencies on the order of hundreds of gigahertz. 4 Once the entire THz frequency range is fully accessible by convenient radiation sources, it is obvious that the next important step towards applications is the development of suitable detectors. Like any other type of electromagnetic radiation, THz waves or pulses can be detected by coherent or incoherent means. Most coherent detection schemes utilize frequency conversion, whereas incoherent methods are based on the heat production of absorbed radiation. Typical examples of heat detectors include Si-bolometers or pyroelectric crystals like deuterated triglycerine-sulfate ͑DTGS͒; on the other hand, Schottky diode mixers, 5 nonlinear optical crystals like ͕110͖ ZnTe, 6 and gated photoconductive antennas are typical coherent detection schemes. 7 As a further incoherent solution, semiconductor-based quantum-type approaches like biased superlattices have attracted some attention.8 Bolometers are in general highly sensitive, but like all heat-based detection schemes, they are intrinsically slow and built for very low temperature operation only.9 DTGS detectors and pyroelectric crystals offer the advantage of faster detection at the prize of reduced sensitivity. Finally, extrinsic photoconductors such as doped Ge detectors are fast and sensitive, but they must be cooled to 4 K. Quite generally, coherent techniques profit from a good sensitivity, but they are experimentally more sophisticated than incoherent ones.10 Although semiconductor quantum devices might not be highly sensitive, their potential for mass fabrication and integration by means of semiconductor device technology is very appealing. This has been proven by different types of quantum well infrared photodetectors ͑QWIPs͒ which work in a variety of different wavelength...

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mentioning

confidence: 99%

Terahertz range quantum well infrared photodetector

Graf¹,

Scalari²,

Hofstetter³

et al. 2004

Applied Physics Letters

199

119

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“…Different types of semiconductor structure, including those based on bulk HgCdTe, 1,2 quantum well, [3][4][5][6] quantum dot, 7,8 and type-II strained superlattices, 9 have been studied and tested in an attempt to achieve this aim. In addition, theoretical studies have been undertaken to understand and try to solve the problems associated with achieving uncooled IR detection.…”

Section: Introductionmentioning

confidence: 99%

Performance improvements of a split-off band infra-red detector using a graded barrier

Pitigala

Lao

Perera

et al. 2014

Journal of Applied Physics

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Uncooled split-off band infrared detectors have been demonstrated with an operational device response in the 3–5 μm range. We have shown that it is possible to enhance this device response through reducing the recapture rate by replacing one of the commonly used flat barriers in the device with a graded barrier, which was grown using a “digital alloying” approach. Responsivity of approximately 80 μA/W (D* = 1.4 × 108 Jones) were observed at 78 K under a 1 V applied bias, with a peak response at 2.8 μm. This is an improvement by a factor of ∼25 times compared to an equivalent device with a flat barrier. This enhancement is due to improved carrier transport resulting from the superlattice structure, and a low recapture rate enabled by a reduced distance to the image force potential peak in the graded barrier. The device performance can be further improved by growing a structure with repeats of the single emitter layer reported here.

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“…Since the responsivity, R i , depends linearly on the photoconductive gain, we could multiply our values with the above factor 250 in order to have a fairer comparison with the performance of QWIPs. 3 Clearly, the large capture and small escape probabilities severely reduce the photoconductive gain and thus the responsivity of our detectors. However, in our case the noise gain, g n ϭ(1Ϫp c /2)/Np c , becomes small, 11,12 meaning that we might profit from an improved noise behavior.…”

mentioning

confidence: 99%

“…Recently, new applications such as high speed modulators and detectors based on intersubband transitions have been proposed. 3 Because of the short intrinsic carrier lifetimes observed in intersubband transitions, this type of infrared detector should have superior high frequency properties than comparable HgCdTe-based interband photodetectors. 4 Although the responsivity of QWIPs, especially at room temperature, is relatively low, the possibility of having them monolithically integrated with active components, for instance lasers, offers entirely new avenues for telecommunication systems based on intersubband devices.…”

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confidence: 99%

Quantum-cascade-laser structures as photodetectors

Hofstetter

Beck

Faist

2002

Applied Physics Letters

120

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We evaluated two different quantum-cascade-laser structures as photodetectors. The first device was a 5.3 m two-phonon-resonance structure, and the second one a 9.3 m bound-to-continuum transition laser. The 5.3 m structure had a peak responsivity of 120 A/W at 2200 cm Ϫ1 and functioned up to 325 K. On the other hand, the 9.3 m device also worked up to 297 K but had a lower responsivity of 50 A/W at 1330 cm Ϫ1 . Since the absorption peak of these devices can be shifted by applying an external bias, we envision interesting applications in free-space optical telecommunications.Quantum well infrared detectors ͑QWIPs͒ for thermal imaging systems have been investigated extensively for several years. Today's state-of-the-art systems consist of arrays with thousands of QWIPs which can detect thermal images at high resolution and with a low background limited infrared performance temperature. 1,2 The detectors used in these systems are optimized for high sensitivity and function usually at cryogenic temperatures. Recently, new applications such as high speed modulators and detectors based on intersubband transitions have been proposed. 3 Because of the short intrinsic carrier lifetimes observed in intersubband transitions, this type of infrared detector should have superior high frequency properties than comparable HgCdTe-based interband photodetectors. 4 Although the responsivity of QWIPs, especially at room temperature, is relatively low, the possibility of having them monolithically integrated with active components, for instance lasers, offers entirely new avenues for telecommunication systems based on intersubband devices. The most important feature of detectors in such systems is their high speed which determines the maximal bandwidth. Although telecommunication experiments using directly modulated quantum-casade ͑QC͒ lasers have so far relied on HgCdTe detectors, 5,6 intersubband detectors and intra-cavity modulators seem to be better suited for this task. Accordingly, we present in this article two examples of how QC structures can be used as infrared photodetectors at temperatures up to room temperature.Growth of the samples for the presented experiments was based on molecular beam epitaxy of lattice matched In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As layers for S1848 and of straincompensated In 0.6 Ga 0.4 As/In 0.44 Al 0.56 As layers for S1869. Both structures were grown on InP substrates; S1848 was a bound-to-continuum transition laser at 9.3 m, while S1869 was a two-phonon-resonance laser structure with an emission wavelength of 5.3 m. The two lasers along with the corresponding measurement results are described in detail elsewhere. 7,8 The 9.3 m bound-to-continuum device was processed into 200ϫ200 m 2 square mesa structures with a 45°facet for efficient light coupling. For the 5.3 m device, we chose a 300-m-long and 40-m-wide ridge waveguide architecture with a cleaved back facet and a 45°tilted front facet. For testing, we soldered the samples on copper heat sinks and mounted them into a liquid nitrogen flow cry...

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High absorption (>90%) quantum-well infrared photodetectors

Cited by 67 publications

References 6 publications

Terahertz range quantum well infrared photodetector

Terahertz range quantum well infrared photodetector

Performance improvements of a split-off band infra-red detector using a graded barrier

Quantum-cascade-laser structures as photodetectors

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