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Kouhestani C.,TEAM Technologies Inc. | Nguyen D.D.,COSMIAC | Kambour K.E.,Leidos | Devine R.A.B.,Think Strategically | And 3 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics

The authors have used transient photovoltage measurements to evaluate carrier relaxation times (τ) in P3HT:PCBM based photocells over a wide range of open circuit voltages. Satisfactory agreement is found with data obtained by low frequency impedance measurements. The authors find the differential capacitance measurements yield data consistent with the theoretical value expected based on Langevin recombination. The Langevin coefficient is three orders of magnitude smaller than the theoretical one. For the low light levels, the relaxation time variation is determined by the RC time constant behavior of the photodiode. © 2015 American Vacuum Society. Source

Nguyen D.D.,COSMIAC | Kouhestani C.,COSMIAC | Kambour K.E.,Leidos | Bersuker G.,SEMATECH | Devine R.A.B.,Think Strategically
IEEE International Integrated Reliability Workshop Final Report

The existence of multiple, physically distinct components of Negative Bias Temperature Instability requires a measurement methodology which allows the extraction of each component independently. In this paper we present results obtained at room temperature, which minimizes both the interface state and switching trap components, allowing us to explore the trapping of holes at preexisting defects in the oxide. This is done for both SiON and HfO2/SiO2 oxide stacks of similar total thickness. Results are presented for both pseudo-DC and pulse stressing including the dependence of the pulse measurements on duty cycle. A two trap model using the Tewksbury formalism is proposed to predict the results. © 2014 IEEE. Source

Nguyen D.D.,COSMIAC | Kouhestani C.,COSMIAC | Kambour K.E.,Leidos | Devine R.A.B.,Think Strategically
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics

Using a rapid data acquisition methodology, the authors examine the time dependent recovery of the "permanent" component of charge build-up due to the negative bias temperature instability in Si based p-channel field effect transistors in inversion and n-channel devices in accumulation. The authors find clear evidence for recovery of the charge associated with interface states for elevated temperatures (≥150 °C) and for extended times (trecover ∼ 20 000 s). Recovery appears to begin at shorter times for p-channel devices than for n-channel. An explanation is advanced both for the mechanism of interface state annealing and for the difference observed between p and n channel devices. © 2014 American Vacuum Society. Source

Kambour K.E.,Leidos | Kouhestani C.,TEAM Technologies Inc. | Nguyen D.D.,COSMIAC | Devine R.A.B.,Think Strategically
Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics

The need for more reliable and radiation hard complementary metal-oxide-semiconductor compatible devices coupled with an ever increasing shrinkage of device dimensions has led naturally to interest in metal-oxide semiconductor field-effect transistors having nontraditional geometries. One such geometry is the gate-all-around transistor, which has been suggested to be less sensitive than its planar counterpart to the effect of charge build-up at the semiconductor-insulator interface such as that induced by irradiation. In order to explore the radiation hardness of such a structure, the effect of radiation on gate-all-around n-type metal-oxide-semiconductor devices was investigated by computing the effect of charging on the threshold voltage of the device. The radiation sensitivity in ideal structures is explored, and the greater radiation sensitivity found experimentally in some devices is explained. © 2016 American Vacuum Society. Source

Kambour K.,SAIC | Rosen N.,Air Force Research Lab | Kouhestani C.,COSMIAC | Nguyen D.,COSMIAC | And 6 more authors.
IEEE Transactions on Nuclear Science

Initial experimental work has demonstrated that X-ray bombardment of organic-based photocells (specifically P3HT:PCBM-based) leads to a reduction in the open-circuit voltage (Voc) without apparent change in the carrier relaxation time. The variation of Voc was suggested to be due to the injection and trapping of holes near the anode, which resulted in a decrease in the built-in potential. We have extended the experimental measurements to higher total dose (∼ 1300(SiO2)). Using standard inorganic modeling tools, a device model of the organic cell has been developed and predictions made. These predictions have been compared to the results of the previous and new experimental measurements and they demonstrate reasonable agreement between the two, thereby supporting the initial charge buildup hypothesis. Questions about the origin and behavior of the photo-carrier relaxation arise. © 1963-2012 IEEE. Source

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