Tantalum nitride （TAN） and nichrome （NiCr） are the two most common materials used as thin film resistors （TFR） for monolithic microwave integrated circuits （MMIC） based on AlGaN/GaN high electron mobility tran...Tantalum nitride （TAN） and nichrome （NiCr） are the two most common materials used as thin film resistors （TFR） for monolithic microwave integrated circuits （MMIC） based on AlGaN/GaN high electron mobility transistors （HEMTs）. In this study,we compare the reliability of the two materials used as TFRs on a semi-insulation 4H SiC substrate. Through the comparison between NiCr and TaN thin-film resistor materials, we find the square resistor （Rs） of TaN TFR increases as the annealing temperature increases. However, the R s of NiCr TFR shows the opposite trend. We also find the change of the TaN Rs and contacted resistor （Re） is smaller than the NiCr. After O2 plasma exposure in RIE,the TaN R s only decreases 0.7Ω,or about 2.56%, and R c increases 0.1Ω,or about 6.6%, at an annealing temperature of 400℃. In contrast, the NiCr R s and R c show large changes at different annealing temperatures after O2 plasma exposure. In conclusion,TaN is more stable during plasma exposure after 400℃ annealing in N2 ambient.展开更多
This paper proposes an integration mechanism to help the owners and designers to integrate sustainability issues into design process, communicate with stakeholders and achieve consensus. Literature concerning engineer...This paper proposes an integration mechanism to help the owners and designers to integrate sustainability issues into design process, communicate with stakeholders and achieve consensus. Literature concerning engineering design, decision making and environment assessment were reviewed. Sustainability disputes in construction projects were analyzed and owners and designers were interviewed to understand the evolvement of these issues. Key success factors of other successful integration projects were also referenced. An integration mechanism including procedures was established along with traditional design process. Four integration steps were developed： organize integration team, propose integration issues, determine acceptance criteria, and evaluate alternatives; and four integration dimensions were also identified： appeals, decision making and execution, stakeholders, and experts. A matrix was formed by the four integration steps and four dimensions. A rigor index was proposed to measure the quality of the integration process. Finally, the mechanism was tested on a construction project with sustainability controversy to check its validity. The study results show that the integration mechanism can help incorporate sustainability issues and achieve consensus if followed rigorously. The integration matrix systematically examines the eight key integration factors under the four dimensions. The rigor index can explain the quality in integrating sustainability issues into engineering design. The mechanism provides a useful tool for the owners and designers to cope with the sustainability decision making difficulties.展开更多
文摘Tantalum nitride （TAN） and nichrome （NiCr） are the two most common materials used as thin film resistors （TFR） for monolithic microwave integrated circuits （MMIC） based on AlGaN/GaN high electron mobility transistors （HEMTs）. In this study,we compare the reliability of the two materials used as TFRs on a semi-insulation 4H SiC substrate. Through the comparison between NiCr and TaN thin-film resistor materials, we find the square resistor （Rs） of TaN TFR increases as the annealing temperature increases. However, the R s of NiCr TFR shows the opposite trend. We also find the change of the TaN Rs and contacted resistor （Re） is smaller than the NiCr. After O2 plasma exposure in RIE,the TaN R s only decreases 0.7Ω,or about 2.56%, and R c increases 0.1Ω,or about 6.6%, at an annealing temperature of 400℃. In contrast, the NiCr R s and R c show large changes at different annealing temperatures after O2 plasma exposure. In conclusion,TaN is more stable during plasma exposure after 400℃ annealing in N2 ambient.
文摘This paper proposes an integration mechanism to help the owners and designers to integrate sustainability issues into design process, communicate with stakeholders and achieve consensus. Literature concerning engineering design, decision making and environment assessment were reviewed. Sustainability disputes in construction projects were analyzed and owners and designers were interviewed to understand the evolvement of these issues. Key success factors of other successful integration projects were also referenced. An integration mechanism including procedures was established along with traditional design process. Four integration steps were developed： organize integration team, propose integration issues, determine acceptance criteria, and evaluate alternatives; and four integration dimensions were also identified： appeals, decision making and execution, stakeholders, and experts. A matrix was formed by the four integration steps and four dimensions. A rigor index was proposed to measure the quality of the integration process. Finally, the mechanism was tested on a construction project with sustainability controversy to check its validity. The study results show that the integration mechanism can help incorporate sustainability issues and achieve consensus if followed rigorously. The integration matrix systematically examines the eight key integration factors under the four dimensions. The rigor index can explain the quality in integrating sustainability issues into engineering design. The mechanism provides a useful tool for the owners and designers to cope with the sustainability decision making difficulties.
