The comprehensive study of liquid phase oxidation on GaAs-based transistor applications
The GaAs-based HEMTs with gate oxide and HBTs with surface passivation prepared by liquid phase oxidation (LPO) will be demonstrated. As compared to the Schottky-gate HEMTs, the lower gate leakage currents, higher breakdown voltages, and improved RF performances make the proposed technique suitable for high-power and high-speed applications. Moreover, the HBTs with oxide passivation possess the characteristics of lower surface recombination currents, higher breakdown voltage, and improved higher dc current gain.
Liquid phase oxidation for InGaP/GaAs HBT passivation
Native oxide films grown near room temperature by liquid phase oxidation (LPO) on p+-GaAs, n-InGaAs and n-InGaP are investigated. Their applications to heterojunction bipolar transistors (HBTs) are also demonstrated and characterized. With the LPO as surface passivation, the dc current gain β of the HBT devices increases sevenfold in low collector current regimes, and it also shows wider collector regimes from 8.3 × 10−11 A to 0.1 A. In addition, a larger breakdown voltage and lower surface recombination current can be obtained. This provides the possibility of promising implementations in low-power electronics and communication applications. Comparisons between devices with LPO passivation and those with sulfur treatment on the InGaP/GaAs HBTs are also discussed.
Cognitive Correlaretes of Physics Achievement of Some Nigeria Senior Secondary Students
Some cognitive correlates of physics achievement of some Nigeria senior secondary students were considered in the study. Specifically, the study examined the relationship between measures of student’s field independency. Cognitive tasks, formal reasoning and their achievement in physics. Purposive and stratified random sampling techniques were employed to obtain a sample of 524 senior secondary two students from six education zones in Kogi State of Nigeria. Three instruments were used. They are science Reasoning Tasks (SRTs). Group Embedded Figures Test (GEFT) and Physics Achievement Test (PAT). Data analysis using multiple regressions reveals that measures of students’ fields’ independency and cognitive tasks predicted student’s achievement in physics generally. However, only measure of field independency predicted students’ achievement in physics in the higher order cognitive demand questions. Measures of formal reasoning had no significant relationship with students’ achievements in physics generally or in higher order cognitive demand questions in physics. However, the overall relationships between measures of field independency, cognitive tasks, formal reasoning and students’ achievement in physics generally and in higher order cognitive demand questions in physics were both significant. Educational implications of these findings were discussed.