Depletion region

About: Depletion region is a research topic. Over the lifetime, 9393 publications have been published within this topic receiving 145633 citations.

Silicon carbide field effect transistor with increased avalanche withstand capability

Abstract: A vertical SiC trench MOSFET power switching FET includes a gate electrode in the trench. The MOSFET adds a buried region of a first conductivity type, more heavily doped than a base layer of the first conductivity type, to the base layer except adjacent to the trench. The buried region is preferably disposed in the base layer, or between a drift layer of a second conductivity type and the base layer. The region of the first conductivity type is optionally disposed below the bottom of the trench to encourage expansion of the depletion layer of the MOSFET. A depletion-type vertical SiC MESFET of the invention includes a buried region of the first conductivity type in a base layer of a second conductivity type. A Schottky electrode on a portion of the base layer above the buried region ensures adequate expansion of a depletion layer.

Synergistic Doping of Fullerene Electron Transport Layer and Colloidal Quantum Dot Solids Enhances Solar Cell Performance

Abstract: The spatial location of the predominant source of performance-limiting recombination in today's best colloidal quantum dot (CQD) cells is identified, pinpointing the TiO2:CQD junction; then, a highly n-doped PCBM layer is introduced at the CQD:TiO2 heterointerface. An n-doped PCBM layer is essential to maintain the depletion region and allow for efficient current extraction, thereby producing a record 8.9% in overall power conversion efficiency.

Low-frequency noise in UHV/CVD epitaxial Si and SiGe bipolar transistors

Abstract: In this work a comprehensive investigation of low-frequency noise in ultrahigh vacuum/chemical vapor deposition (UHV/CVD) Si and SiGe bipolar transistors is presented. The magnitude of the noise of SiGe transistors is found to be comparable to the Si devices for the identical profile, geometry, and bias. A comparison with different technologies demonstrates that the SiGe devices have excellent noise properties compared to AlGaAs/GaAs heterojunction bipolar transistors (HBT's) and conventional Si bipolar junction transistors (BJT's). Results from different bias configurations show that the 1/f base noise source is dominant in these devices. The combination of a 1/Area dependence on geometry and near quadratic dependence on base current indicates that the 1/f noise sources are homogeneously distributed over the entire emitter area and are probably located at the polysilicon-Si interface. Generation/recombination (Gm) noise and random telegraph signal (RTS) noise was observed in selected Si and SiGe devices. The bias dependence and temperature measurements suggest that these G/R centers are located in the base-emitter space charge region. The activation energies of the G/R traps participating in these noise processes were found to be within 250 meV of the conduction and valence band edges.

Guard ring design for high voltage operation of silicon detectors

Abstract: The termination of the depletion zone towards the non-depleted part of silicon affects the total device leakage current, the long term stability, the noise level and the radiation hardness of silicon detectors. This paper describes computer simulations and experiments to develop guard ring structures for use in silicon detectors requiring thick depletion layers, high operating voltages and biasing beyond depletion without increase in the leakage current and the noise. Computer simulation of a simplified structure is used to understand the influence from the oxide charges and the substrate doping concentration for a segmented guard structure with several floating diffusion strips. Results from the simulations are compared with measurements on devices. The numerical results are found to be in agreement with experimental data. It is found that segmented guard structures with floating diffusion strips have high breakdown voltages and low leakage currents. The effects of floating metal field plates over the oxide between the floating diffusion strips are studied on two different guard structures by measuring the potential on the diffusion strips and the leakage currents in the guard and active diode. The results show that floating intermediate field plates reduces the influence from oxide charges and stabilises the device against environmental influence.

Built-in electric field assisted nucleation and coercive fields in ferroelectric thin films

Abstract: A model of ferroelectric switching in thin films which also exhibit semiconducting properties is presented. The two principle assumptions upon which the model is based are (1) that the threshold field for reverse domain nucleation, E cm, is much greater than the field required for domain wall motion, E cm, and (2) that the electrode-film interface is modeled as a metal-semiconductor interface. A film thickness dependence of the coercive field is qualitatively predicted by the model. When applied to the experimentally determined thickness dependence of coercive field in lead-zirconate-titanate thin films, the model predicts a donor concentration, N D, of 1018 cm−3 and a space charge surface layer thickness, W, of 0.2 μm.