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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 38 for “"Surface recombination"”.
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Influence of defects and impurities on solar cell performance
… and a negligible effect of front and back surface recombination velocity. This assumption can cause a significant error as the current mc-Si technology provides good surface passivation by SiN:H and very effective back surface fields. This work is an extension of previous models that use …
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Assessing materials quality for high efficiency electricity generation
… used to measure the bulk lifetime as well as the surface recombination lifetime of minority carriers in both n- and p-type Silicon of various doping concentrations. The surface recombination velocity was calculated from the measurement of surface recombination lifetime and analyzed after the …
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Surface and bulk passivation of multicrystalline silicon solar cells by silicon nitride (H) layer : modeling and experiments
… mechanisms in Si solar cells, specifically, the surface and bulk passivation by hydrogen-rich PECVD silicon nitride (SiN :H) antireflection layer on multicrystalline silicon (me-Si) solar cells. The passivation of silicon surface can be achieved in two ways: by field-effect passivation and/or by …
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Decoupling bulk- and surface-limited lifetimes in thin kerfless silicon wafers using spectrally resolved transient absorption pump-probe spectroscopy and computer simulations
… wafer thickness, however, the impact of surface recombination increases and dominates the effective lifetime measured by conventional methods. Therefore, the ability to decouple bulk-limited lifetime from surface-limited lifetime is desirable, ideally without the need for surface …
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High Performance Silicon Optoelectronic Devices Enabled by Photocarrier Transport-Recombination Engineering and Surface Light-Trapping Topologies
Photocarrier generation, transport, recombination and extraction are fundamental processes for modern semiconductor optoelectronic devices. The need for light-trapping strategies to enhance the overall optical absorption of semiconductor devices has inspired a wide variety of studies and …
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Laser beam induced current studies of Hg1-xCdxTe photodiodes
… beam that is scanned across the semiconductor surface, between two shorted ohmic contacts located at remote positions on either side of the scanned area. The LBIC image is then a two-dimensional map of the steady-state current-flow as a function of laser position. However, despite its …
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The Effect of Ambient on Photoluminescence from GaN
… be explained by changes in the nonradiative recombination rate at the surface (recombination mechanism). We therefore assume that in vacuum and acid vapor some surface species are desorbed or passivated, resulting in a decreased nonradiative recombination rate and increased PL intensity.
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High-speed Type-II GaAsSb/InP DHBTs for mixed-signal IC applications
… width scales down, the emitter peripheral surface recombination current becomes a significant portion of the total base current, leading to reduced current gain. Chapter 6 discusses the development of an emitter ledge process for the doping-graded Type-II GaAsSb/InP DHBT. Compared with …
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Spectroscopic characterization of the near-surface electronic structure of surface-modified III-V semiconductors
Investigations of the near-surface electronic structure of n$\sp+$-GaAs and n$\sp+$-InAs are presented. Recent studies of the GaAs surface have been carried out which demonstrate that the surface states which arise from termination of the crystal lattice, which are known to cause pinning of the …
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Understanding defects in germanium and silicon for optoelectronic energy conversion
… are determined to be largely a result of recombination due to threading dislocations. We estimate that recombination by threading dislocations becomes negligible when threading dislocation density is </~ 4 10⁶ cm-². We developed a process for incorporation of colloidal quantum dots (QD) …
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Solar Cells with Passivating Contacts − Investigation of Their Temperature- and Illumination-Dependent Performance and Surface Passivation
… contacts have been developed to eliminate the recombination at the Si/metal interface which significantly impacts the cell performance due to the extremely high surface recombination velocity. Up to now, the characterisation of the performance of solar cells with passivating contacts has been …
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Study of Semiconducting Nanomaterials: Photoelectrochemistry and Dynamic Light Scattering
… across interfaces. We studied how to control surface recombination on ZnO nanomaterials (specifically, nanowires) for efficient charge carrier collection. We concluded that the presence of iodide in the solution stabilizes ZnO nanowires due to the faster rate of iodide oxidation for hole (h+) …
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Fabrication and Characterization of Electrically Injected Photonic Crystal Light Emitters
… to the gain medium and reduces non-radiative recombination at the semiconductor air interfaces formed by the photonic crystal air holes. The use of a submicron diameter oxide aperture enables optical and electrical confinement. The design parameters of the photonic crystal nanocavity structure …
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Characterization of temperature profile in furnace and solubility of iron in silicon
… defects (in addition to Fei-Bs / Fei), surface recombination, and high sensitivity of the calculated iron concentration to the measured minority carrier lifetimes.
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Advanced Electron-Beam Techniques for Solar Cell Characterization
… Firstly, the advantage of the subsurface imaging of scanning electron acoustic microscopy (SEAM) was utilized to characterize the structural properties of saw-damage-induced defects and the non-destructive nature of SEAM could enable accurate optimization of saw-damage etch process …
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Enhanced performance of optical sources in III-V materials using photonic crystals
… crystals for III-V optical sources: nonradiative recombination pathways introduced at the high dielectric contrast interfaces of the photonic crystal. Chapter 1 begins the thesis by providing a theoretical and historical framework for photonic crystals, and lays the foundation for the design of …
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Development of electrical and optical devices for next generation high-speed optical interconnects
… than double DC current gain β by suppressing surface recombination, but with trade-offs in ideality factor, yield, base resistance, and fT/fmax. Together, these results provide the process capability and device understanding needed to co-optimize Cryo-VCSEL sources and InP-DHBT electronics for …
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Electrical properties of silicon surfaces and interfaces
… with diminishing device size. First, alternative surface passivation chemistries are investigated to meet the narrowing process tolerances for high quality silicon surfaces. Second, Si-based light emitting devices are studied to address a longer-term move towards photons instead of electrons for …
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Empirical correlation of minority carrier lifetime to detect density profile in germanium on silicon heteroepitaxy
… from the Ge/Si interface and relating the surface recombination velocity on Ge film surface average lifetime within Ge film, and recombination velocity at the Ge/Si interface. Two photoconductance decay techniques were used in this work: quasi-steady-state photoconductance decay and …
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Designing Planar Silicon Solar Cells for Singlet Fission Sensitization
… oxide passivation layer growth conditions and surface treatments, Si(100) versus Si(111) orientation, and junctions formed by diffusion doping versus ion implantation. Complementary surface photovoltage (SPV) measurements on matching optical stacks show evidence of an illumination-induced …
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