Critical Analysis Of Sic Sit Design And Performance Based Upon Material And Device Properties

Recently, the need for high power, high frequency devices continues to grow with the increase in wireless communication, radar systems, HDTV, digital communication, and other military application of the RF spectrum. Traditionally when higher power is needed, one needs to either combine the output power of multiple devices or use vacuum tubes, which are still uncontested at very high power levels, capable of up to a few hundred kilowatts at 5 GHz [11]. But wide band gap semiconductor devices capable of competing in this application. Moreover, the static induction transistor (SIT) in silicon carbide can provide very high total power at microwave frequency. This is due to the vertical structure of the SIT which consists of a vertical channel that is defined by a mesa with gate electrodes of the Schottky type to control the current between a top side source contact and a drain contact on the backside of the wafer. This thesis demonstrates that through careful modeling by means of simulations and inclusion of all significant device physics, good agreement is reached between theoretical prediction and simulation results. It is shown in particular that by careful choice of the device critical parameters, such as mesa width, gate length, and contact resistance, SIT should be able to obtain cut-off frequency up to 42 GHz and shown temperature simulation results of SIT

Ligand Assisted Surface Stoichiometry Control for Bright and Stable Ag2S Nanocrystals

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Ag2S Quantum Dots with Reduced Ag+ ion Vacancies

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Synthesis of Non-toxic Ag-Based NIR Quantum Dots and Its Application into Photoelectronic Device

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Synthesis of Non-toxic Ag-Based NIR Quantum Dots and Its Application into Photoelectronic Device

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Ligand Exchange Strategies toward Bright and Stable Ag2S Nanocrystals with Ag-rich, S-rich and Stoichiometric Surface Stoichiometry

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Augmented Photoluminescence in a Conjugated Polymer by the Incorporation of CdSe/CdS Quantum Dots

We investigated the photophysical interactions between CdSe/CdS quantum dots (QDs) and a conjugated polymer (CP, P3HT). The photoluminescence intensity of P3HT in the QDs/P3HT hybrid system is significantly enhanced compared to that of the neat P3HT system. We found via transient absorption spectroscopy that the energy level differences at the interfaces between P3HT and QDs resulted in delayed relaxation dynamics of the P3HT singlet (S1) excitons and suppressed polaron formation. Thus, the radiative recombination of the S1 excitons occurs frequently in the hybrid system than in the neat P3HT system. Our findings on the CP-based hybrid system may provide important information to improve the efficiencies of optoelectronic devices, such as organic light-emitting diodes.11Nsciescopu

Facile Ligand Exchange of Ionic Ligand-Capped Amphiphilic Ag₂S Nanocrystals for High Conductive Thin Films

A surface ligand modification of colloidal nanocrystals (NCs) is one of the crucial issues for their practical applications because of the highly insulating nature of native long-chain ligands. Herein, we present straightforward methods for phase transfer and ligand exchange of amphiphilic Ag2S NCs and the fabrication of highly conductive films. S-terminated Ag2S (S–Ag2S) NCs are capped with ionic octylammonium (OctAH+) ligands to compensate for surface anionic charge, S2–, of the NC core. An injection of polar solvent, formamide (FA), into S–Ag2S NCs dispersed in toluene leads to an additional envelopment of the charged S–Ag2S NC core by FA due to electrostatic stabilization, which allows its amphiphilic nature and results in a rapid and effective phase transfer without any ligand addition. Because the solvation by FA involves a dissociation equilibrium of the ionic OctAH+ ligands, controlling a concentration of OctAH+ enables this phase transfer to show reversibility. This underlying chemistry allows S–Ag2S NCs in FA to exhibit a complete ligand exchange to Na+ ligands. The S–Ag2S NCs with Na+ ligands show a close interparticle distance and compatibility for uniformly deposited thin films by a simple spin-coating method. In photoelectrochemical measurements with stacked Ag2S NCs on ITO electrodes, a 3-fold enhanced current response was observed for the ligand passivation of Na+ compared to OctAH+, indicating a significantly enhanced charge transport in the Ag2S NC film by a drastically reduced interparticle distance due to the Na+ ligands