The MBE growth and optimization of high performance terahertz frequency quantum cascade lasers

Li, L H; Zhu, Jingxuan; Chen, L; Davies, A. G.; Linfield, E. H.

doi:10.1364/oe.23.002720

Cited by 42 publications

(23 citation statements)

References 28 publications

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“…Further, it seems that there exits an obvious change for the scaling factor dP CW /dL. For the devices with L≤2.9 mm, the P CW is nearly linear with L as observed in some previous reports 7,12 and dP CW /dL is ∼83 mW/mm. When L is longer than 2.9 mm, dP CW /dL is ∼-28 mW/mm.…”

supporting

confidence: 75%

“…Since the first demonstration in 2002, 3 THz QCLs have witnessed a rapid development. Till date, the frequency ranges from 1.2 to 5.0 THz 4,5 and the highest output power in pulsed wave (PW) mode achieves more than 1 W. 6,7 However, the output power in continuous wave (CW) mode is still limited to 138 mW since 2006. 8 This is an impediment toward many important applications in spectroscopy, imaging, remote sensing, etc.…”

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confidence: 99%

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High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

et al. 2016

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Terahertz quantum cascade lasers with a record output power up to ∼0.23 W in continuous wave mode were obtained. We show that the optimal 2.9-mm-long device operating at 3.11 THz has a low threshold current density of 270 A/cm2 at ∼15 K. The maximum operating temperature arrived at ∼65 K in continuous wave mode and the internal quantum efficiencies decreased from 0.53 to 0.19 for the devices with different cavity lengths. By using one convex lens with the effective focal length of 13 mm, the beam profile was collimated to be a quasi Gaussian distribution.

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confidence: 75%

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confidence: 99%

High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

et al. 2016

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“…In addition, the THz radiation is strongly diffracted from what is essentially a sub-wavelength slit at the facet, which makes it difficult to collect and collimate the THz beam [5]. While the highest THz QCL temperature performances have been achieved in MM QCL waveguides, the highest emitted THz QCL powers [6][7][8] have been recorded with surface plasmon waveguides where a significant portion of the laser field resides outside the active region. The increased spatial extent of the surface plasmon mode leads to an improvement of both the out-coupling performance and the beam diffraction at the expense of a reduction in the confinement factor of the mode in the active region.…”

Section: Introductionmentioning

confidence: 99%

“…Variants of this design emitting at higher frequencies have set several THz QCL power records when processed into surface plasmon waveguides [7,8]. In this study THz QCLs are processed as MM waveguides with a 13-µm-thick active region, 95-µmridge width, and a length of 1.58 mm.…”

Section: Introductionmentioning

confidence: 99%

Improving the Out-Coupling of a Metal-Metal Terahertz Frequency Quantum Cascade Laser Through Integration of a Hybrid Mode Section into the Waveguide

Fobbe

Nong

Schott

et al. 2016

J Infrared Milli Terahz Waves

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“…A p-GaAs/Al x Ga 1Àx As heterojunction IR detector was grown on a semi-insulating GaAs substrate by molecular beam epitaxy 19 ( Fig. 1(a)).…”

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confidence: 99%

Effect of a current blocking barrier on a 2–6 μm p-GaAs/AlGaAs heterojunction infrared detector

Chauhan

Perera

et al. 2016

Applied Physics Letters

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We report the performance of a 30 period p-GaAs/Al x Ga 1Àx As heterojunction photovoltaic infrared detector, with graded barriers, operating in the 2-6 lm wavelength range. Implementation of a current blocking barrier increases the specific detectivity (D*) under dark conditions by two orders of magnitude to $1.9 Â 10 11 Jones at 2.7 lm, at 77 K. Furthermore, at zero bias, the resistance-area product (R 0 A) attains a value of $7.2 Â 10 8 X cm 2 , a five orders enhancement due to the current blocking barrier, with the responsivity reduced by only a factor of $1.5. Published by AIP Publishing.[http://dx.doi.org/10.1063/1.4952431] Infrared (IR) detectors and imaging systems are becoming increasingly important in a diverse range of military and civilian applications. In recent years, significant attention has been paid to incorporating current blocking architectures into detector designs. For example, AlGaAs current blocking layers have been utilized in quantum dot IR photodetectors (QDIPs) both to enhance performance [1][2][3][4][5][6] and to achieve elevated operating temperatures. [7][8][9] Similarly, in type II InAs/ GaSb superlattice (T2SL) IR photodetectors, majority carrier (hole) blocking layers have been implemented, 10 as well as electron blocking and hole blocking unipolar barriers in complementary barrier infrared detectors (CBIRD) 11 and p-type-intrinsic-n-type (PbIbN) photodiodes. 12 Furthermore, dark current suppressing structures were also demonstrated, such as conduction band barriers in nBn photodetectors 13,14 and XBn barrier photodetectors. 15 In general, the main goal in these architectures is to lower the dark current, but with a relatively small compromise to the photocurrent, thus achieving a significant improvement in the specific detectivity (D*).Due to the mature growth and established processing technology of p-GaAs/Al x Ga 1Àx As, these materials systems have become increasingly attractive for demonstrating heterojunction interfacial workfunction IR photodetectors (HEIWIP), 16 which operate up to room temperature. 17 Furthermore, replacing the constant Al x Ga 1Àx As barrier with a graded barrier, achieved by tuning the Al mole fraction (x), was found to enable photovoltaic operation as well. 18 This is advantageous over photoconductive operation as it offers thermal noise limited performance and reduced power consumption. In this letter, we report the effect of a current blocking barrier (CBB) on a 30 period p-GaAs/Al x Ga 1Àx As IR detector with graded barriers, which shows a photoresponse at 77 K in the $2-6 lm range under photovoltaic operation. We observe an approximately five orders of magnitude higher resistance-area product (R 0 A) at zero bias, resulting in a two orders of magnitude improvement in D*, with the responsivity compromised only by a factor of $1.5 at zero bias, compared to performance without the CBB.A p-GaAs/Al x Ga 1Àx As heterojunction IR detector was grown on a semi-insulating GaAs substrate by molecular beam epitaxy 19 ( Fig. 1(a)). The active region of the ph...

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The MBE growth and optimization of high performance terahertz frequency quantum cascade lasers

Cited by 42 publications

References 28 publications

High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

Improving the Out-Coupling of a Metal-Metal Terahertz Frequency Quantum Cascade Laser Through Integration of a Hybrid Mode Section into the Waveguide

Effect of a current blocking barrier on a 2–6 μm p-GaAs/AlGaAs heterojunction infrared detector

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