2,389 research outputs found
Distributed Trap Levels and Hot-Electron Trapping in Power GaN HEMTs Characterization and Modeling
No full textGallium Nitride (GaN)-based high electron mobility transistors (HEMTs) are rapidly emerging as front-runners in high-power mm-wave circuit applications. Possible targets that would benefit of the advantages of GaN–based devices include efficient power supplies, DC/DC converters and AC/DC adapters, as well as the field of radars and telecommunications.
Despite the recent commercial success of GaN-based devices, internal physical mechanisms are often not completely understood and still constitute a challenge to the development of a mature GaN-based technology. Besides the difficulties of growing a high–quality GaN material, point defects at interfaces play a major role in terms of reliability.
In the present thesis, several aspect of the device instability have been investigated from both and experimental and theoretical point of view. Throughout this thesis, our goal is to build a quantitative and qualitative understanding of the main factors undermining the device stability under real application conditions.
By comparing Hard and Soft switching turn-on commutations, we demonstrated how turn-on stress plays a major role in the on-resistance degradation, while off-state bias does not have a relevant influence on device properties. Furthermore, by repeating the experiment on several devices with different L_GD, we were able to demonstrate the important role of electric field in determining the R_ON increase and to rule out a significant contribution of self-heating.
Then, in order to observe the full trapping and de-trapping kinetics of hot-electrons we focused on semi-ON stress analysis by means of a custom setup able to perform Drain Current Transient (DCT) analysis. Firstly, by focusing on the trapping phase, a physical understanding of the hot electron phenomena in GaN-based HEMTs is developed with a cross-comparison between theoretical analysis and experimental data. Linear dependency on the applied electric field and logarithmic dependency on the current density in determining the severity of current collapse are found. Results provide important information for the modeling of hot-electron trapping kinetics in GaN-based power transistors. The first 10 us of operation are critical in determining the current collapse during stress.
Secondly, by focusing on the recovery phase, we propose a general methodology for mapping the properties (activation energy, cross sections) of a distribution of surface/interface states in GaN-based electronic devices. To prove the validity and usefulness of the model, the extracted map distributions are used as input for TCAD simulations. The results obtained by TCAD closely match the experimental transient curves, thus confirming the effectiveness of the developed technique.
The theoretical knowledge built along this thesis allowed us to propose a new approach for compact modeling of the stretched exponential trapping/de-trapping kinetics of p-GaN HEMTs is proposed. Novel insight on the GaN HEMT dynamic performance degradation is given highlighting how the criticality of a trap is dependent on its location in the capture and emission time map. The duty cycle plays a key role in determining the performance degradation trajectory, while the frequency is related to the amplitude of the capture and emission process per cycle.Gallium Nitride (GaN)-based high electron mobility transistors (HEMTs) are rapidly emerging as front-runners in high-power mm-wave circuit applications. Possible targets that would benefit of the advantages of GaN–based devices include efficient power supplies, DC/DC converters and AC/DC adapters, as well as the field of radars and telecommunications.
Despite the recent commercial success of GaN-based devices, internal physical mechanisms are often not completely understood and still constitute a challenge to the development of a mature GaN-based technology. Besides the difficulties of growing a high–quality GaN material, point defects at interfaces play a major role in terms of reliability.
In the present thesis, several aspect of the device instability have been investigated from both and experimental and theoretical point of view. Throughout this thesis, our goal is to build a quantitative and qualitative understanding of the main factors undermining the device stability under real application conditions.
By comparing Hard and Soft switching turn-on commutations, we demonstrated how turn-on stress plays a major role in the on-resistance degradation, while off-state bias does not have a relevant influence on device properties. Furthermore, by repeating the experiment on several devices with different L_GD, we were able to demonstrate the important role of electric field in determining the R_ON increase and to rule out a significant contribution of self-heating.
Then, in order to observe the full trapping and de-trapping kinetics of hot-electrons we focused on semi-ON stress analysis by means of a custom setup able to perform Drain Current Transient (DCT) analysis. Firstly, by focusing on the trapping phase, a physical understanding of the hot electron phenomena in GaN-based HEMTs is developed with a cross-comparison between theoretical analysis and experimental data. Linear dependency on the applied electric field and logarithmic dependency on the current density in determining the severity of current collapse are found. Results provide important information for the modeling of hot-electron trapping kinetics in GaN-based power transistors. The first 10 us of operation are critical in determining the current collapse during stress.
Secondly, by focusing on the recovery phase, we propose a general methodology for mapping the properties (activation energy, cross sections) of a distribution of surface/interface states in GaN-based electronic devices. To prove the validity and usefulness of the model, the extracted map distributions are used as input for TCAD simulations. The results obtained by TCAD closely match the experimental transient curves, thus confirming the effectiveness of the developed technique.
The theoretical knowledge built along this thesis allowed us to propose a new approach for compact modeling of the stretched exponential trapping/de-trapping kinetics of p-GaN HEMTs is proposed. Novel insight on the GaN HEMT dynamic performance degradation is given highlighting how the criticality of a trap is dependent on its location in the capture and emission time map. The duty cycle plays a key role in determining the performance degradation trajectory, while the frequency is related to the amplitude of the capture and emission process per cycle
Author Meets Reader: Not the Marrying Kind: A Feminist Critique of Same-Sex Marriage
No full textThis is an audio recording of an author meets reader session held at the SLSA Annual Conference, University of York, 27 March 2013. Nicola Barker's book, Not the Marrying Kind: A Feminist Critique of Same-Sex Marriage, was the winner of the 2013 Hart SLSA Book Prize. In the session she introduces the book and then engages in discussion about it with Daniel Monk
South Thompson Valley and Pinantan official settlement plan.
No full textThe recommended policies contained in this plan provide the Thompson-Nicola Regional District with the means to protect and enhance the agricultural economic base, regulate the supply and location of rural residential growth, guide commercial and industrial development and satisfy the historical, recreational, social and environmental concerns of the settlement plan area.Not peer reviewedPlanning documen
Rural Residential Study
No full textThe Thompson-Nicola Regional District has recently been grappling with some of the basic problems and conflicts of trying to provide for rural residential lot demand and, at the same tie, trying to protect the resources, aesthetics and social climate of existing rural area.Not peer reviewedstudydraf
The Role of Coordination and Cooperation for Bt-maize cultivation in Brandenburg, Germany
No full textSince 2006, several varieties of transgenic Bt-maize are approved for commercial cultivation in Germany. The German regulatory framework for growing these crops comprises ex-ante regulations as well as ex-post liability rules to protect conventional and organic farming from possible negative side effects of transgenic plants and to ensure co-existence. Public regulation is also suspected to impose additional costs to those farmers who intend to plant Bt-maize. We address the question how Bt-maize growing farmers perceive the additional costs of regulation and whether coordination or cooperation takes place in order to diminish these costs. In 2006, we carried out a case study in the Oderbruch region (Brandenburg, Germany) comprising eight Bt-maize growing farmers and six adjacent neighbours. The predominantly large farms chose intrafarm coordination to manage the construction of buffer zones within their own fields and to avoid the planting of Bt-maize close to their neighbours. Inter-farm coordination or cooperation with adjacent farmers was not regarded necessary to achieve co-existence.Coordination, Cooperation, Bt-maize, Crop Production/Industries,
TNRD Thompson-Nicola Regional District The First 25 Years 1967-1992: Municipalities and Electoral Areas Working Together as Regional Government to Tackle Common Challenges
No full textNot peer reviewe
Author Meets Reader Session: 'Not the Marrying Kind'
No full textThis is an audio recording of an author meets reader session held at the SLSA Annual Conference, University of York, 27 March 2013. Nicola Barker's book, Not the Marrying Kind: A Feminist Critique of Same-Sex Marriage, was the winner of the 2013 Hart SLSA Book Prize. In the session she introduces the book and then engages in discussion about it with Daniel Monk
"An Acquired Taste": The Internal and External Posture of Nicola Barker, Metamodernist Author
No full textThis thesis looks at how Nicola Barker's internal and external posture are construed on the basis of her last three books, The Cauliflower® (2016), H(A)PPY (2017), and I Am Sovereign (2019), how different institutions react to these books and whether that posture can be considered metamodernist. The theoretical framework and methodology builds on Meizoz's notion of posture, the singular way of occupying a position within the literary field, as defined by Bourdieu. As for metamodernism, multiple important sources are examined, starting with Vermeulen and Van den Akker. The research concludes that Nicola Barker can indeed be considered a metamodernist author and her posture seems to construed as that of a working-class author with a nonconformist and anti-establishment attitude, as well as an unconventional and transgressively intermedial approach that, despite her abundantly employed irony, always seems to contain a moral core
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