GaN-on-silicon transistors with reduced current collapse and improved blocking voltage by means of local substrate removal

AbstractHigh quality undoped AlGaN/GaN high electron mobility transistors(HEMTs) structures have been gorwn by Hydride Vapor Phase Epitaxy (HVPE). The morphology of the films grown on Al2O3 substrates is excellent with root-mean-square roughness of ∼0.2nm over 10×10μm2 measurement area. Capacitance-voltage measurements show formation of dense sheet of charge at the AlGaN/GaN interface. HEMTs with 1μm gate length fabricated on these structures show transconductances in excess of 110 mS/mm and drain-source current above 0.6A/mm. Gate lag measurements show similar current collapse characteristics to HEMTs fabricated in MBE- or MOCVD grown material.

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DEEP LEVELS' ACTIVATION ENERGY DEPENDENCE ON MEASUREMENT MODES

CAD/EDA, MODELING AND SIMULATION IN MODERN ELECTRONICS: COLLECTION OF SCIENTIFIC PAPERS OF THE III INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE ◽

10.30987/conferencearticle_5e028210156607.46541827 ◽

2019 ◽

Author(s):

Aleksey Bogachev ◽

Vladimir Krylov

Keyword(s):

Activation Energy ◽

Gallium Arsenide ◽

Energy Dependence ◽

Deep Level ◽

Deep Levels ◽

Blocking Voltage

The results of an experiment to determine the activation energy of a deep level in a gallium arsenide mesastructure by capacitive relaxation spectroscopy of deep levels at various values of the blocking voltage are considered.

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Biofilm Structure – An Important and Neglected Parameter in Waste Water Treatment

Water Science & Technology ◽

10.2166/wst.1989.0283 ◽

1989 ◽

Vol 21 (8-9) ◽

pp. 805-814 ◽

Cited By ~ 15

Author(s):

F. R. Christensen ◽

G. Holm Kristensen ◽

J. la Cour Jansen

Keyword(s):

Wastewater Treatment ◽

Structural Changes ◽

Waste Water Treatment ◽

Experimental Investigations ◽

Biofilm Reactors ◽

Substrate Removal ◽

Treatment Processes ◽

Laboratory Reactor ◽

Biofilm Structure ◽

Kinetics Of

Experimental investigations on the kinetics of wastewater treatment processes in biofilms were performed in a laboratory reactor. Parallel with the kinetic experiments, the influence of the biofilm kinetics on the biofilm structure was studied at macroscopic and microscopic levels. The close interrelationship between biofilm kinetics and structural changes caused by the kinetics is illustrated by several examples. From the study, it is evident that the traditional modelling of wastewater treatment processes in biofilm reactors based on substrate removal kinetics alone will fail in many cases, due to the inevitable changes in the biofilm structure not taken into consideration. Therefore design rules for substrate removal in biofilms used for wastewater treatment must include correlations between the removal kinetics and the structure and development of the biological film.

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The Use of Anoxic Selectors for the Control of Low F/M Activated Sludge Bulking

Water Science & Technology ◽

10.2166/wst.1989.0263 ◽

1989 ◽

Vol 21 (6-7) ◽

pp. 609-619 ◽

Cited By ~ 13

Author(s):

Y.-J. Shao ◽

David Jenkins

Keyword(s):

Organic Matter ◽

Activated Sludge ◽

Pilot Plant ◽

Detention Time ◽

Substrate Removal ◽

Batch System ◽

Sludge Bulking ◽

N Removal ◽

Soluble Substrate ◽

Activated Sludge Systems

Laboratory and pilot plant experiments on anoxic selector activated sludge systems were conducted on two wastewaters in some cases supplemented with nitrate, acetate or glucose. To prevent bulking sufficient anoxic selector detention time and nitrate levels must be available to reduce selector effluent soluble COD to below 100 mg/l and to reduce readily metabolizable organic matter to virtually zero (< 1 mg/l). Soluble COD/NO3-N removal stoichiometry is in the range 6.0-6.7. Selector systems have elevated soluble substrate removal and denitrification rates compared to CSTR systems. These rates are not affected greatly by temperature (20-25°C) for CSTR sludges but are for selector sludges. Upon exhaustion of nitrate in a selector soluble COD leaks out of the activated sludge in significant amounts. Thiothrix sp. and type 021N denitrify only to NO2 and at much slower rates than Zoogloearamigera does to N2. A sequencing batch system provides an optimistic estimate of the SVI that can be obtained by an anoxic selector system.

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Quantification of the kinetic differences between communities isolated from completely mixed activated sludge systems operated with or without a selector using a novel respirometric method

Water Science & Technology ◽

10.2166/wst.1994.0567 ◽

1994 ◽

Vol 30 (11) ◽

pp. 255-261 ◽

Cited By ~ 5

Author(s):

Barth F. Smets ◽

Timothy G. Ellis ◽

Stephanie Brau ◽

Richard W. Sanders ◽

C. P. Leslie Grady

Keyword(s):

Oxygen Consumption ◽

Activated Sludge ◽

Physiological Changes ◽

Biodegradation Kinetics ◽

Substrate Removal ◽

Biomass Yields ◽

Selection For ◽

Single Oxygen ◽

Activated Sludge Systems

This study quantified the kinetic differences in microbial communities isolated from completely mixed activated sludge (CMAS) systems that were operated either with or without an aerobic selector preceding the main reactor. A new respirometric method was employed that allowed the determination of biodegradation kinetics from single oxygen consumption curves, thereby minimizing physiological changes to the examined communities during the assay. Results indicated that increased values for Ks and μmax for acetate, phenol, and 4-chlorophenol degradation were measured in the CMAS system operated with a selector. The biomass yields on acetate, phenol, and 4-chlorophenol were very similar in both systems. These findings indicate that the operation of CMAS systems with aerobic selectors may result in the selection for degrading populations with higher Ks and μmax values for both biogenic and xenobiotic organic compounds, and that substrate storage in the selector only partially contributes to increased substrate removal rates.

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