Engineering Commons^™

Development Of Micro-Sized Algan Deep Ultraviolet Light Emitting Diodes And Monolithic Photonic Integrated Circuits, Richard Speight Floyd Iii

Theses and Dissertations

III-Nitride materials-based visible emission LEDs have emerged as a disruptive technology in the fields of lighting,ⁱ) communications,^ii,iii,iv) and displays.^v,vi) Shorter wavelength LEDs in the DUV spectral region (210nm – 360nm) with ultra-wide bandgap (UWBG) Al_xGa_1-xN active layers are now poised to displace toxic Mercury-based light sources.^vii) Over the past decade AlGaN LEDs operating in the deep ultra-violet (DUV) spectral region (200 nm < λ_emission < 300 nm) have been deployed in novel applications including autonomous drone-based sterilization and sanitization systems, ^viii) point-of-use water purification systems, ^ix) photo-therapeutics,x) gas sensors,xi) and non-line-of-sight (NLOS) communications.^xii) Similarly, DUV light detectors using ultra-wide bandgap (UWBG) Al …

Increased Detectivity And Low Temperature Performance Analysis Of Sub-20Μm Micropixel Array A1gan Uv Photodiodes, Samia Islam

Theses and Dissertations

This thesis is divided into two sections. At first, we demonstrate ~1.5x detectivity increase in AlGaN photodiodes on sapphire using distributed micropixel arrays with 5-15 µm pixel diameter. This is due to the ~10x larger chip footprint of the 5um diameter micropixel arrays compared to planar control structures with identical p contact area. The responsivity of the larger areas was the same as that of the control structure despite the larger footprint while the dark currents, an indicator of noise, remained unchanged. The photocurrent generated between pixels was collected due to transmission line effects connecting the pixels separated by 5um, …

Ultrawide Bandgap Algan-Channel Metal Oxide Semiconductor Heterostructure Field Effect Transistors With High-K Gate Dielectrics, Md Abu Shahab Mollah

Theses and Dissertations

Ultra-wide Band Gap (UWBG) (E_G > 3.4 eV) Al_xGa_1-xN channel devices are promising candidates for compact next-generation power electronics due to the scaling of the breakdown field with alloy composition. The huge opportunity in consumer electronics is the major driving force behind the recent developments of UWBG AlGaN-channel HEMTs. One of the most critical issues limiting the device performance at high power level is device degradation primarily caused by gate leakage current. Use of SiO₂ gate insulator is a standard method to suppress gate leakage but it causes threshold voltage shift towards more negative requiring …

Design, Fabrication, And Characterization Of Pseudomorphic And Quasi-Pseudomorphic Algan Based Deep Ultraviolet Light Emitting Diodes Over Sapphire, Fatima Asif

Theses and Dissertations

III-Nitride based deep ultraviolet (UV) light emitting diodes (LEDs) emitting below 280nm has the potential to replace mercury lamps currently used in the systems for water/air purification, germicidal and medical instruments sterilization applications. However, this potential has not yet been fully realized as the output power, quantum efficiency and lifetime of deep UV-LEDs have been limited by the large number of dislocations in the active region of the devices, arising from the lattice mismatched sapphire substrate, which has been the substrate of choice due to its high transparency to deep UV radiation. To reduce dislocations in the active region of …

Dislocation Reduction In Silicon Doped High Aluminum Content Algan Layers For Deep Uv Optoelectronic Devices, Hung-Chi Chen

Theses and Dissertations

III-Nitride based deep ultraviolet (UV) light emitting diodes (LEDs) are prospective candidates to replace the conventional bulky, expensive and environmentally harmful mercury lamp as new UV light sources, used in the applications of water and air purification, germicidal and biomedical instrumentation systems, etc. Due to the lack of native substrates and poor carrier injection, AlGaN-based deep UV LED is suffering from low optical power and low overall efficiency, which prevents the availability of low cost, high efficiency deep UV LED on the market.

This dissertation is focused on improving the efficiency of deep UV LEDs, by improving the base template …

Effects Of N-Type Doping On Algan Material Quality, Devendra Diwan

Theses and Dissertations

The field of group III-nitride semiconductors has seen incredible developments during last couple of decades. They are recognized as the most promising materials for a wide field of optoelectronics and electronic devices. Their bandgap ranges from 6.2 eV for AlN to 0.7 eV for InN, covering a wide spectral range from infrared (1.77 mm) to deep ultraviolet (200 nm). Their direct bandgap makes them useful for fabricating optoelectronic devices such as light emitting diodes (LEDs), laser diodes (LDs), and photodetectors. III-nitride semiconductor materials also possess strong bond strengths and exhibit good structural, chemical and thermal stability. These properties make it …