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Full-Text Articles in Physics

Stacking 2d Materials, Michael Hernandez, John C. Mann Mar 2017

Stacking 2d Materials, Michael Hernandez, John C. Mann

Seaver College Research And Scholarly Achievement Symposium

Monolayer Transition Metal Dichalcogenides are atomically thin semi-conductors that are considered quasi 2D materials due to their extremely small thickness. It has been observed that atomically thin crystals exhibit different physical properties than their bulk counterparts due to quantum confinement effects. We are attempting discover new physical properties by developing a technique to stack two different monolayer crystals, MoS2 and MoSe2.


Analysis Of Gan/Alxga1−Xn Heterojunction Dual-Band Photodetectors Using Capacitance Profiling Techniques, Laura E. Byrum Dec 2009

Analysis Of Gan/Alxga1−Xn Heterojunction Dual-Band Photodetectors Using Capacitance Profiling Techniques, Laura E. Byrum

Physics and Astronomy Theses

Capacitance-voltage-frequency measurements on n+-GaN/AlxGa1−xN UV/IR dual-band detectors are reported. The presence of shallow Si-donor, deep Si-donor, and C-donor/N-vacancy defect states were found to significantly alter the electrical characteristics of the detectors. The barrier Al fraction was found to change the position of the interface defect states relative to the Fermi level. The sample with Al fraction of 0.1 shows a distinct capacitance-step and hysteresis, which is attributed to C-donor/N-vacancy electron trap states located above the Fermi level (200 meV) at the heterointerface; whereas, the sample with Al fraction of 0.026 shows negative ...


Uncooled Infrared Photon Detection Concepts And Devices, Viraj Vishwakantha Jayaweera Piyankarage Mar 2009

Uncooled Infrared Photon Detection Concepts And Devices, Viraj Vishwakantha Jayaweera Piyankarage

Physics and Astronomy Dissertations

This work describes infrared (IR) photon detector techniques based on novel semiconductor device concepts and detector designs. The aim of the investigation was to examine alternative IR detection concepts with a view to resolve some of the issues of existing IR detectors such as operating temperature and response range. Systems were fabricated to demonstrate the following IR detection concepts and determine detector parameters: (i) Near-infrared (NIR) detection based on dye-sensitization of nanostructured semiconductors, (ii) Displacement currents in semiconductor quantum dots (QDs) embedded dielectric media, (iii) Split-off band transitions in GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. A far-infrared ...


Semiconductor Quantum Structures For Ultraviolet-To-Infrared Multi-Band Radiation Detection, Gamini Ariyawansa Aug 2007

Semiconductor Quantum Structures For Ultraviolet-To-Infrared Multi-Band Radiation Detection, Gamini Ariyawansa

Physics and Astronomy Dissertations

In this work, multi-band (multi-color) detector structures considering different semiconductor device concepts and architectures are presented. Results on detectors operating in ultraviolet-to-infrared regions (UV-to-IR) are discussed. Multi-band detectors are based on quantum dot (QD) structures; which include quantum-dots-in-a-well (DWELL), tunneling quantum dot infrared photodetectors (T-QDIPs), and bi-layer quantum dot infrared photodetectors (Bi-QDIPs); and homo-/heterojunction interfacial workfunction internal photoemission (HIWIP/HEIWIP) structures. QD-based detectors show multi-color characteristics in mid- and far-infrared (MIR/FIR) regions, where as HIWIP/HEIWIP detectors show responses in UV or near-infrared (NIR) regions, and MIR-to-FIR regions. In DWELL structures, InAs QDs are placed in an InGaAs ...


Threshold Extension Of Gallium Arsenide/Aluminum Gallium Arsenide Terahertz Detectors And Switching In Heterostructures, Mohamed Buhary Rinzan Dec 2006

Threshold Extension Of Gallium Arsenide/Aluminum Gallium Arsenide Terahertz Detectors And Switching In Heterostructures, Mohamed Buhary Rinzan

Physics and Astronomy Dissertations

In this work, homojunction interfacial workfunction internal photoemission (HIWIP) detectors based on GaAs, and heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors based mainly on the Gallium Arsenide/Aluminum Gallium Arsenide material system are presented. Design principles of HIWIP and HEIWIP detectors, such as free carrier absorption, photocarrier generation, photoemission, and responsivity, are discussed in detail. Results of p-type HIWIPs based on GaAs material are presented. Homojunction detectors based on p-type GaAs were found to limit their operating wavelength range. This is mainly due to band depletion arising through carrier transitions from the heavy/light hole bands to the split off ...