SACM - United States of America
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9668
Browse
Item Restricted (1) CREATIVITY IN THE FADING ISLAMIC EMPIRE. (2) EFFECTS OF ARAB- ISRAELI CONFRONTATION ON SAUDI POETRY. (3) THE WAHHABIYA OF ARABIA - THE MAHDIYA OF THE SUDAN.(Saudi Digital Library) MUHAMMAD M. ABAHSAIN43 0Item Restricted 7 0Item Restricted 5 0Item Restricted (1) THE PROCESS OF RURAL COMMERCIALIZATION IN NIGERIA AND SENEGAL: THE CASE OF PEANUT PRODUCTION. (2) ISLAM IN EAST AFRICA.(Saudi Digital Library) MOHAMMAD ABDUL-KAREIM HABIB4 0Item Restricted 1- CHARACTERIZING THE PERFORMANCE OF AMALGAM BONDING AT VARIOUS INTERFACES. 2- EFFECT OF OCCLUSAL LOAD CYCLING ON THE MARGINAL INTEGRITY OF ADHESIVE CLASS V RESTORATIONS.(Saudi Digital Library) YOUSEF ABDULRAHMAN H. KHODAIR5 0Item Restricted 1-D Fourier Ptychographic Microscopy(Saudi Digital Library) MOHAMMED SAADI TURKEY ALOTAIBI; Dr. Luis Grave de Peralta0 0Item Restricted 24 0Item Restricted 4 0Item Restricted 18F-FDG PET/CT-based Radiomics for the Prediction of Radiochemotherapy Treatment Outcomes of Cervical Cancer(Saudi Digital Library) BADERALDEEN ABDULMAJEED M ALTAZI; Dr. Eduardo G. Moros1 0Item Restricted 2D MATERIALS BASED HETEROSTRUCTURES FOR QUANTUM TUNNELING: A LITHOGRAPHY FREE TECHNIQUE(Saudi Digital Library) ALI IBRAHIM MOHAMMED ALZAHRANI; Gamini SumanasekeraABSTRACT 2D MATERIALS BASED HETEROSTRUCTURES FOR QUANTUM TUNNELING: A LITHOGRAPHY FREE TECHNIQUE Ali Alzahrani March 31st, 2022 Two-dimensional electron gas (2DEG) systems have played a vital role in the development of superior electronic devices including tunnel junctions consisting of two such 2DEG systems. With the advent of the new 2D electronic material systems, it has opened a new route for 2D–2D tunneling in such extended systems In this study, we have utilized a plasma enhanced chemical vapor deposition (PECVD) technique to directly deposit graphene (nanowalls) and h-BN on Si/SiO2 substrates to construct two-dimensional material based, vertically stacked electron tunneling devices free of expensive and cumbersome microfabrication steps. In the first study, we fabricated direct quantum tunneling devices by depositing atomically thin tunnel barriers of h-BN as the tunneling barrier with equally doped (p-doped under ambient conditions) graphene nanowalls as the active electrode layers (top and bottom) on Si/SiO2 substrates. Current-voltage (I-V) measurements for varying h-BN thicknesses of these single barrier tunneling devices showed linear I-V characteristics at low bias but an exponential dependence at higher bias. Our measurements of the electron tunnel current through the barrier demonstrated that the h-BN films act as a good tunnel barrier. The barrier thickness dependent tunneling current was in good agreement with the tunnelling currents computed using the Bardeen transfer Hamiltonian approach with equally doped top and bottom graphene electrodes. Presence of negative differential resistance (NDR) is characteristic of the current–voltage relationship of a resonant tunneling device, enabling many unique applications. NDR arises at a voltage bias corresponding to aligned band structures of the 2D systems, causing a sharp peak in the tunnelling current. The existence of devices with NDR has been reported since the late 1950's in devices that contained degenerately doped p-n junctions with thin oxide barriers (tunnel diodes) and double barrier heterojunction devices where quantum tunneling effects are utilized. The NDR in the I-V characteristics of these devices has been used in many applications involving microwave/millimeter wave oscillators, high speed logic devices and switches. We investigated NDR phenomenon in our graphene/h-BN systems in two different routes. In the first case, graphene/h-BN/graphene single barrier device, the bottom and top graphene layers were unequally doped. One of the graphene layers was n-type doped using ammonia or hydrazine. Nitrogen doping using ammonia was accomplished during the growth by incorporating ammonia in the PECVD system. Hydrazine doping was accomplished by exposing the graphene to hydrazine vapor in vacuum. The unequal doping of graphene causes alignment of the band structures of graphene systems giving rise to NDR. The tunnelling devices consisting of unequally doped graphene with a single barrier shows resonant quantum tunneling with the presence of a pronounced peak in the current corresponding to NDC whose peak current value and the voltage value depend on the doping levels. The results are explained according to the modified Bardeen tunneling model. Next, resonant tunneling behavior was demonstrated in Graphene/h-BN/Graphene/h-BN/Graphene double barrier (DB) devices by directly depositing graphene and h-BN successive layers on Si/SiO2 substrates using PECVD. DB Tunneling junctions with various barrier widths were investigated (by varying the thickness of the second graphene layer). The I-V parameters of tunneling current at room temperature demonstrated resonant tunneling with negative differential conductance. A quantum mechanical double barrier tunneling model was used to explain the phenomenon, by solving the Schrödinger's equation in either side of the s12 0Item Restricted 2D MATERIALS BASED HETEROSTRUCTURES: A LITHOGRAPHY FREE METHOD(Saudi Digital Library) ADEL BANDAR AZWAN ALRUQI; Dr. Gamini Sumanasekera9 0Item Restricted 2D seismic data and gas chimney interpretation in the South Taranaki Graben, New Zealand(Saudi Digital Library) Taqi Talib S Alzaki; Liu, Kelly H.0 0Item Restricted 3-D SIMULATION AND OPTIMIZATION OF FORGING OF A COMPLEX BEVEL GEAR USING THE FINITE ELEMENT METHOD .(Saudi Digital Library) ADEL KHALID FOZAN0 0Item Restricted 3-HYDROXY FATTY ACIDS INDUCE RETINAL PIGMENT EPITHELIAL CELL LIPOAPOPTOSIS(Saudi Digital Library) MONA KASSEM E HADIDI; Sathish Kumar Natarajan0 0Item Restricted 3.3KV, MEGAWATT LEVEL MODULAR MULTILEVEL INVERTER FOR HYBRID/FULL ELECTRIC AIRCRAFT(University of Dayton, 2024-08-06) Dahneem, Ahmed; Cao, DongHybrid/Full electric aircraft (HEA/FEA) represents an attractive concept due to its potential to reduce CO2 emissions, decrease fossil-fuel consumption, enhance overall aircraft efficiency, and lower operational costs. As technology progresses towards hybrid/full electric aircraft, the development of high-performance motor drive systems becomes imperative. This necessity introduces new constraints, particularly in low-pressure environments. Designing for high-altitude applications requires careful consideration to prevent issues like partial discharge and power system failures in the air. Converters must exhibit ultra-high efficiency, high power density, and exceptional reliability. While wide band-gap devices, such as Silicon-carbide based Metal Oxide Silicon Field Effect Transistors (SiC-MOSFETs), offer improved switching and high-temperature performance over silicon counterparts, their integration into HEA/FEA applications remains challenging. The high switching speed of SiC-MOSFETs reduces switching losses and facilitates the design of high-density inverters. However, selecting suitable devices is critical for designing high-power-rated inverters. Moreover, the risk of partial discharge increases at high voltages in conditions of low air pressure, posing a threat to inverter longevity by compromising system insulation. This thesis evaluates three distinct inverter/converter topologies comprehensively to determine the optimal circuit topology for HEA/FEA applications. The study explores design strategies to ensure busbar integrity, preventing partial discharge without compromising parasitic control. Throughout the thesis, a three-phase megawatt-scale inverter and a 3.3 kV, 288 A power module are designed, fabricated, and tested to validate the proposed design strategies.20 0Item Restricted 30‐day all‐cause prediction model for readmissions for heart failure patients: a comparative study of machine learning approaches(Saudi Digital Library) AMAL ABDULLAH M BUKHARI; Sagar Kamarthi, Ph.D7 0Item Restricted 3D Bioprinting: New Horizon In Skin Implants(Saudi Digital Library) BAYAN BADERBASIM A ALARISHI; Professor Christian Bach11 0Item Restricted 3D FINITE ELEMENT MODELING OF LABORATORY HYDRAULIC FRACTURE EXPERIMENTS(Saudi Digital Library) Naif Bandar Alqahtani0 0Item Restricted 3D MODELING, ANALYSIS, AND DESIGN OF A TRAVELING-WAVE TUBE USING A MODIFIED RING-BAR STRUCTURE WITH RECTANGULAR TRANSMISSION LINES GEOMETRY(Saudi Digital Library) Sadiq Ali H Alhuwaidi; Dr. Heather Song0 0Item Restricted 3D SEISMIC ATTRIBUTE ANALYSIS AND MACHINE LEARNING FOR RESERVOIR CHARACTERIZATION IN TARANAKI BASIN, NEW ZEALAND(Saudi Digital Library) AAMER ALI H ALHAKEEM; Dr. Kelly Liu0 0