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3 results on '"Javadyan A"'

1. Simple Requirement to Passivating Film/GaAs Interface for Avalanche Breakdown Suppression.

Author

Vainshtein, Sergey, Javadyan, Valeriy, Duan, Gouyong, Tsendin, Konstantin, and Kostamovaara, Juha

Subjects
*INTEGRATED circuit passivation, *SEMICONDUCTORS, *ELECTRONS, *CHALCOGENIDES, *GALLIUM arsenide
Abstract

Shown recently superfast (picosecond range) switching and copious sub-THz emission from a GaAs avalanche n+-p-n0-n+ bipolar junction transistor (BJT) makes the task of premature surface breakdown suppression critically important. Here we show that surface breakdown can be suppressed even for negatively beveled mesa by creating sufficiently high (~1012 cm-2) density of negative surface charge. This charge can be cause by surface-trapped avalanche-generated electrons or, alternatively, formed on the semiconductor/passivation film interface by proper selection of a passivation material. In particular we observed excellent passivation properties of a chalcogenide glass. [ABSTRACT FROM AUTHOR]

Published
2011

2. Chalcogenide glass surface passivation of a GaAs bipolar transistor for unique avalanche terahertz emitters and picosecond switches.

Author

Vainshtein, Sergey, Javadyan, Valeri, Duan, Guoyong, Tsendin, Konstantin, Hovhannisyan, Rafael, and Kostamovaara, Juha

Subjects
*ELECTRIC properties of chalcogenide glass, *BIPOLAR transistors, *TERAHERTZ technology, *EMITTER-coupled logic circuits, *BREAKDOWN voltage, *ELECTRIC charge
Abstract

The ultra-narrow 'collapsing' field domains discovered recently in avalanching GaAs bipolar junction transistor provide a physical basis for designing unique THz emitters and superfast switches. Reliability in devices operating near their volume breakdown voltage requires decisive suppression of premature surface breakdown. We demonstrate here complete, durable surface breakdown suppression through simple deposition of a massive chalcogenide glass layer on the mesa surface by means of a negative charge formed at the interface. [ABSTRACT FROM AUTHOR]

Published
2012
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3. Hemodynamic instability associated with increased risk of death or brain injury in neonates with hypoxic ischemic encephalopathy.

Author

Mohammad, K., Hicks, M., Buchhalter, J., Esser, M. J., Irvine, L., Thomas, S., Scott, J., Javadyan, J., and Kamaluddeen, M.

Subjects
*HEMODYNAMICS, *BRAIN injury treatment, *HEPATIC encephalopathy, *NEONATAL mortality, MORTALITY risk factors
Abstract

OBJECTIVE: To determine the association between hemodynamic instability requiring inotropes and brain injury or death in neonates with hypoxic ischemic encephalopathy (HIE). METHODS: Retrospective cohort study of 221 neonates with HIE. Brain injury was defined using four HIE patterns based on MRI diffusion or T1 changes. The primary outcome was death or brain injury. Secondary outcomes were abnormal MRI, death, and abnormal EEG. Logistic regression was used to examine the risk of death or brain injury with the use of inotropes while adjusting for confounding factors. RESULTS: Brain injury or death occurred more often in neonates who received inotropes (71.1%, 69/97) compared to those who did not (44.3%, 55/124). The use of inotropes was associated with increased risk of death or brain injury (OR 3.11; 95% CI 1.39-7.004) and abnormal MRI (OR 2.78; 95% CI 1.22-6.34) after adjusting for confounding factors. Mortality was significantly higher in neonates exposed to inotropes (21.6%, 21/97) compared with those who did not receive inotropes (4%, 5/124), P < 0.001. CONCLUSION: In infants with HIE, hemodynamic instability requiring inotropes in the first 72 hours of life was associated with increased risk of death or brain injury detected by MRI. [ABSTRACT FROM AUTHOR]

Published
2017
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