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A measurement methodology involving the synchronous switching of gate to source voltage and drain to source voltage (VDS) was proposed for determining the shift of threshold voltage after an AlGaN/GaN heterostructure transistor endures high VDS off-state stress. The measurement results indicated slow electron detrapping behavior. The trap level was determined as (EC – 0.6 eV). Simulation tool was used to analyze the measurement results. The simulation results were consistent with the experimental results; and a relationship between the buffer trap and threshold voltage shift over time was observed.

Researchers have indicated that the collaborative problem-solving space afforded by the collaborative systems significantly impact the problem-solving process. However, recent investigations into collaborative simulations, which allow a group of students to jointly manipulate a problem in a shared problem space, have yielded divergent results regarding their effects on collaborative learning. Hence, this study analysed how students solved a physics problem using individual-based and collaborative simulations to understand their effects on science learning. Multiple data sources including group discourse, problem-solving activities, learning test scores, and questionnaire feedback were analysed. Lag sequential analysis on the data found that students using the two simulations collaborated with peers to solve the problem in significantly different patterns. The students using the collaborative simulations demonstrated active engagement in the collaborative activity; however, they did not transform discussions into workable problem-solving activities. The students using the individual-based simulation showed a lower level of collaboration engagement, starting with individual exploration of the problem with the simulation, followed by group reflection. The two groups also showed significant differences in their learning test scores. The findings and pedagogical suggestions are discussed in the hope of addressing critical activity design issues in using computer simulations for facilitating collaborative learning.