Chia Lung Chang

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The photoexcited carrier lifetimes in ex situ-annealed low temperature growth GaAs are measured with a femtosecond transient absorption experiment. The study encompassed two low temperature growth GaAs films with approximately 0.3% and 0.9% excess arsenic incorporated during growth. The observed lifetimes are found to be a function of the spacing of arsenic(More)
Surface magnetoelastic waves are coupled elastic and magnetic excitations that propagate along the surface of a magnetic material. Ultrafast optical techniques allow for a non-contact excitation and detection scheme while providing the ability to measure both elastic and magnetic components individually. Here we describe a simple setup suitable for(More)
Precipitation processes in the p-type, n-type, and intrinsic GaAs layers grown by molecular beam epitaxy at a low tempera ture were studied by transmission electron microscopy. The average spacing, average diameter, and volume fraction of precipitates were measured as a function of the annealing time for the annealing tempera ture of 700~ Volume fractions(More)
Magnesium oxide (MgO) sensing membranes in pH-sensitive electrolyte-insulator-semiconductor structures were fabricated on silicon substrate. To optimize the sensing capability of the membrane, CF4 plasma was incorporated to improve the material quality of MgO films. Multiple material analyses including FESEM, XRD, AFM, and SIMS indicate that plasma(More)
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