Design, Fabrication, and Characterization of Quantum Cascade Terahertz Emitters PDF Download

Author: Vinod M. Menon
Publisher:
ISBN:
Category : Laser beams
Languages : en
Pages : 230

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Author: Matthias Stecher
Publisher:
ISBN: 9783954041985
Category :
Languages : en
Pages : 97

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Book Description

Author: Shigeru Obayashi
Publisher: Springer
ISBN: 3540709282
Category : Computers
Languages : en
Pages : 972

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Book Description
This book constitutes the refereed proceedings of the 4th International Conference on Evolutionary Multi-Criterion Optimization, EMO 2007, held in Matsushima, Japan in March 2007. The 65 revised full papers presented together with 4 invited papers are organized in topical sections on algorithm design, algorithm improvements, alternative methods, applications, engineering design, many objectives, objective handling, and performance assessments.

Author: Guangchi Xuan
Publisher: ProQuest
ISBN: 9780549387091
Category : DNA.
Languages : en
Pages :

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Book Description
In recent years, new applications in Terahertz (THz) imaging, spectroscopy, ranging and telecommunication had initiated huge research interest in THz emitting devices. There were few suitable sources available, however, in the THz frequency range (1-10 THz). Thus more powerful terahertz sources were strongly desired, especially with higher operating temperatures. This dissertation described two THz emitting devices based on Si and SiC materials that demonstrated much higher operating temperatures than what was previously published. Dry etching with xenon difluoride (XeF 2) was a well-known process for the isotropic removal of silicon. The etching of silicon germanium alloys with XeF 2, however, had not been investigated. Here, the XeF 2 dry etching of SiGe-alloys was characterized versus composition and XeF 2 partial pressures. It was found that the etch rates showed a strong dependence on Ge content of the etched materials. The roughness of the etched surfaces was also investigated. This study provided etch rates versus process conditions and etched surface roughness, which were useful information for accurately fabricating SiGe-based structures and devices. Label-free detection of DNA molecules via electronic methods were also investigated in this dissertation. A device that was similar to conventional metal-oxide-semiconductor (MOS) was described. The current-voltage characteristic was used to investigate the behavior of this Si-based field effect device with DNA solutions of various concentrations and molecular states deposited on the sensing region.

Author: Yue Shen
Publisher:
ISBN:
Category :
Languages : en
Pages : 67

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The THz quantum-cascade vertical-external-cavity surface-emitting-laser (QC-VECSEL) is a recently developed approach for designing high-power, electrically pumped THz lasers with excellent beam quality and broadband tunability. The key component of the QC-VECSEL is an amplifying reflectarray metasurface, based on a subwavelength array of surface radiating metal-metal waveguide antenna elements loaded with QC-laser gain material. Despite its importance, the gain properties of the QC-metasurface are designed by simulation and have only been verified indirectly through observation of the QC-VECSEL lasing characteristics, or by passive FTIR reflectance measurements at room-temperature. THz time-domain spectroscopy (TDS) has been widely used to investigate gain spectra and laser dynamics of THz QC-lasers based on various ridge waveguide geometries. In this thesis, I describe my construction of a THz TDS system and present the first direct spectral measurement using reflection-mode THz TDS of an amplifying QC-metasurface resonant at 2.6 THz under different conditions. The large surface-radiating aperture of the metasurface (1.5 1.5 mm2 in this case) eases free-space TDS measurements compared to ridge waveguide QC-devices with sub-wavelength sized facets.

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 790

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Author: Shuvan Prashant Turaga
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description

Author: R.E. Miles
Publisher: Springer Science & Business Media
ISBN: 1402065035
Category : Technology & Engineering
Languages : en
Pages : 365

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Book Description
Want an overview of where the technology of terahertz detection has been going? Here it is. The technology has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact "electronic" sources such as the quantum cascade laser, two-terminal "Gunn" type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly.

Author: Hong Chang
Publisher:
ISBN:
Category :
Languages : en
Pages : 232

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Book Description
The realization of a two-dimensional electron gas in semiconductor heterostructures due to advanced epitaxial growth techniques has led to novel high-speed devices such as modulation-doped field effect transistors and quantum well lasers. High resolution lithography and pattern transfer techniques now make it possible to further restrict the electronic motion to lower dimensions. A variety of interesting quantum confinement phenomena have been observed in these mesoscopic systems. This thesis describes the design principle, fabrication technique, and transport characterization of various low-dimensional quantum devices. Nanostructure fabrication techniques are presented in detail in the thesis, from high resolution electron beam lithography, pattern transfer techniques, to various one-dimensional (1D) and zero-dimensional (0D) structures with dimensions in the nanometer scale. The effective wire width as well as sidewall damage for both deep etched and shallow etched quantum wires are characterized by the electrical conductance measurement. Artificial lateral surface superlattice (LSSL) structures of line and dot arrays are fabricated using multilayer resist techniques. A typical 1D quantized conductance of $rm 2esp2/h$ is shown in an airbridge split gate device. Plateaulike transport characteristics are demonstrated in airbridge LSSL gate devices due to electrostatic confinement modulation. Laterally tunable single-gate quantum dot and double-bend quantum dot devices are fabricated and investigated. Negative differential conductance is observed at various drain bias conditions in both of these quantum dot devices. Conductance oscillations observed at a temperature as high as 10 K are, to our understanding, the highest temperature reported in similar laterally confined quantum dot devices.

Author: Johann Thomas Trujillo
Publisher:
ISBN:
Category :
Languages : en
Pages : 388

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Book Description