From Photonic Crystal to Subwavelength Micropillar Array Terahertz Lasers

Krall, Michael; Brandstetter, Markus; Deutsch, C.; Detz, Hermann; Andrews, A. M.; Schrenk, W.; Strasser, G.; Unterrainer, K.

doi:10.1109/jstqe.2015.2419216

Cited by 8 publications

(10 citation statements)

References 36 publications

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“…On the basis of current planar technologies, an obvious material choice for nanowire intersubband devices would be GaAs/AlAs. Unfortunately, the pronounced crystal polytypism in GaAs nanowires obtained through the bottom-up approach impedes the application as intersubband devices, and the top-down strategy (patterning and etching) appears as the only alternative . In contrast, for GaN/AlN, the bottom-up method yields the necessary low density of structural defects in spite of the lattice mismatch .…”

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“…Unfortunately, the pronounced crystal polytypism in GaAs nanowires obtained through the bottom-up approach 23 impedes the application as intersubband devices, and the topdown strategy (patterning and etching) appears as the only alternative. 24 In contrast, for GaN/AlN, the bottom-up method 25 yields the necessary low density of structural defects in spite of the lattice mismatch. 26 Thereby, for the III-nitride material system, the nanowire geometry may allow overcoming some of the material quality issues that have hampered the development of III-nitride intersubband devices to date.…”

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Near-Infrared Intersubband Photodetection in GaN/AlN Nanowires

et al. 2017

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Intersubband optoelectronic devices rely on transitions between quantum-confined electron levels in semiconductor heterostructures, which enables infrared (IR) photodetection in the 1-30 μm wavelength window with picosecond response times. Incorporating nanowires as active media could enable an independent control over the electrical cross-section of the device and the optical absorption cross-section. Furthermore, the three-dimensional carrier confinement in nanowire heterostructures opens new possibilities to tune the carrier relaxation time. However, the generation of structural defects and the surface sensitivity of GaAs nanowires have so far hindered the fabrication of nanowire intersubband devices. Here, we report the first demonstration of intersubband photodetection in a nanowire, using GaN nanowires containing a GaN/AlN superlattice absorbing at 1.55 μm. The combination of spectral photocurrent measurements with 8-band k·p calculations of the electronic structure supports the interpretation of the result as intersubband photodetection in these extremely short-period superlattices. We observe a linear dependence of the photocurrent with the incident illumination power, which confirms the insensitivity of the intersubband process to surface states and highlights how architectures featuring large surface-to-volume ratios are suitable as intersubband photodetectors. Our analysis of the photocurrent characteristics points out routes for an improvement of the device performance. This first nanowire based intersubband photodetector represents a technological breakthrough that paves the way to a powerful device platform with potential for ultrafast, ultrasensitive photodetectors and highly efficient quantum cascade emitters with improved thermal stability.

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Near-Infrared Intersubband Photodetection in GaN/AlN Nanowires

et al. 2017

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“…As a consequence, the intersubband absorption is spectrally broad when compared to planar quantum wells [13] or quantum dots [14]. On the other hand, nano-and micropillar arrays for THz emission have been achieved by lithographically defined top-down etching of (Al,Ga)As heterostructures [15][16][17]. Particularly, Amanti et al [15] have shown THz quantum-cascade lasing in a micropillar array, which due to its sub-wavelength dimensions could be considered as photonic metamaterial.…”

Section: Introductionmentioning

confidence: 99%

Near- and mid-infrared intersubband absorption in top-down GaN/AlN nano- and micropillars

Lähnemann,

Browne,

Ajay

et al. 2018

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We present a systematic study of top-down processed GaN/AlN heterostructures for intersubband optoelectronic applications. Samples containing quantum well superlattices that display either near-or mid-infrared intersubband absorption were etched into nano-and micropillar arrays in an inductively coupled plasma. We investigate the influence of this process on the structure and strain-state, on the interband emission and on the intersubband absorption. Notably, for pillar spacings significantly smaller (≤ 1/3) than the intersubband wavelength, the magnitude of the intersubband absorption is not reduced even when 90% of the material is etched away and a similar linewidth is obtained. The same holds for the interband emission. In contrast, for pillar spacings on the order of the intersubband absorption wavelength, the intersubband absorption is masked by refraction effects and photonic crystal modes. The presented results are a first step towards micro-and nanostructured group-III nitride devices relying on intersubband transitions.

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“…Semiconductor nanowires (NWs) have already demonstrated a wide range of promising applications in optoelectronics, electronics, sensing, energy, etc. There is an interest in NWs to improve the performance of intersubband (ISB) devices motivated by: Their low electrical cross‐section implies low electrical capacitance, thus a larger operation bandwidth than planar devices. Owing to antenna effects, this comes without degradation of light absorption.…”

Section: Introductionmentioning

confidence: 99%

“…1 Introduction Semiconductor nanowires (NWs) have already demonstrated a wide range of promising applications in optoelectronics, electronics, sensing, energy, etc. There is an interest in NWs to improve the performance of intersubband (ISB) devices [1][2][3] motivated by:…”

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confidence: 99%