Design and Optimization on a Novel High-Performance Ultra-Thin Barrier AlGaN/GaN Power HEMT With Local Charge Compensation Trench

In this paper, a novel, GaN-based high electron mobility transistor (HEMT) using an ultra-thin barrier (UTB) with a local charge compensation trench (LCCT) is designed and optimized. Because the negative plasma-etching process, as well as the relaxing lattice during the process would introduce equivalent negative charges into the under-LCCT region, the electron will be partially squeezed out from this area. The electric field (E-field) around this region will therefore redistribute smoothly. Owing to this, the proposed LCCT-HEMT performs better in power applications. According to the simulation that is calibrated by the experimental data, the Baliga’s figure of merits (BFOM) of LCCT-HEMT is around two times higher than that of the conventional UTB-HEMT, hinting at the promising potential of proposed HEMT.

Люминесценция примесных Ce-=SUP=-3+-=/SUP=- центров в кристаллах KH-=SUB=-2-=/SUB=-PO-=SUB=-4-=/SUB=-:Ce

The photoluminescence, X-ray luminescence, and cathodoluminescence spectra of KH_2PO_4 : Ce single crystals contain a nonelementary band of radiation with an energy of 3.55 eV and decay time of 27–33 ns. It is formed by fast radiative interconfiguration d → f transitions between the excited and ground states of Ce^3+ ions, with the ground state is split by a crystalline field. In the range of concentrations studied (0.5–3 × 10^–2 wt %), Ce3+ ions enter the KH_2PO_4 : Ce crystal lattice as substitution ions. Local charge compensation takes place by means of defects in the crystal structure that cause luminescence with a large Stokes shift in the region of 2.4–2.2 eV. The presence of hydrogen sublattice defects decreases the efficiency of energy transport by free charge carriers to the luminescent centers. The interaction of defects and impurity centers manifests itself as a slow inertial building-up of the stationary X-ray luminescence yield of Ce^3+ centers.

A key discovery at the TiO2/dye/electrolyte interface: slow local charge compensation and a reversible electric field

Photo-induced absorption spectroscopy on dye-sensitized solar cells reveals reversible electron-induced cation adsorption at the TiO2 surface, resulting in changes of the surface electric field.

Advantages of a Local Charge Compensation System for FIB/SEM Applications on Insulating Materials

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Synthesis and characterization of ultraviolet-emitting cerium-ion-doped SrBPO5 phosphors

The synthesis and characteristics of strontium borate phosphate phosphors doped with cerium ions were investigated in this study. The synthesis of Sr0.95Ce0.05BPO5 in oxidizing atmosphere results in partial conversion of Ce4+ ions into Ce3+ ions. The luminescent characteristics reveal that Ce3+ ions occupy two principal sites in the host. The dominant emission at 317 nm on 275-nm excitation is attributed to Ce3+ ions located at Sr2+ sites without local charge compensation. The weak emission at 330 nm due to 295-nm excitation is ascribed to Ce3+ ions located at Sr2+ sites in association with charge compensatory vacancy. The reduction of Ce4+ ions to Ce3+ ions occurs in Sr0.95Ce0.05BPO5 heated in the reducing atmosphere. For Sr0.9Ce0.05Na0.05BPO5 and Sr0.9Ce0.05Li0.05BPO5 phosphors, enhancement in luminescence is observed due to the codoping of monovalent ions. The increased luminescence of these phosphors is attributed to the decrease in non-radiative energy transfer.