Impurity‐free intermixing of normalGaAs/Al0.54Ga0.46normalAs quantum wells was carried out using SiOx capping layers grown by plasma enhanced chemical vapor deposition followed by rapid thermal annealing at 950°C. A dependence of quantum well intermixing on the quality of dielectric layer was observed, which was varied by changing the silane flow rate, M (40 sccm ≤ M ≤ 480 sccm). The quality of capping layers were determined using Rutherford backscattering spectroscopy, spectroscopic ellipsometry, secondary ion mass spectrometry, Fourier transform infrared spectroscopy, and P‐etch measurements. The porosity and oxygen content of capping layers, and the incorporation of nitrogen during deposition were the main factors influencing the extent of blue shifts achieved in intermixed quantum wells. Substantially higher energy shifts were obtained for capping layers deposited using M < 160 sccm. Slightly overstoichiometric layers which were relatively more porous but containing less nitrogen were obtained for M < 160 sccm. For higher silane flow rates, substoichiometric oxide layers with increased hydrogen and nitrogen contents were obtained. Our results suggested that the mobility of out‐diffusing Ga atoms during annealing was enhanced by film porosity but was suppressed with increasing nitrogen content in the capping layer. © 2000 The Electrochemical Society. All rights reserved.

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The feasibility of using the YAG laser as a tool to thermally machine integrated circuits has been studied. Results

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Terminal lakes throughout the American West provide important amenity and environmental values, but many are shrinking due to reduced inflows and warming temperatures. In California's Imperial Valley, agricultural water use reductions diminish inflows supporting the Salton Sea, a terminal desert lake and important environmental amenity for both the region and the state as a whole. The costs of these reduced inflows are difficult to monetize yet complicate management decisions. We assess the costs of potential future drought‐induced transfers by linking novel hydrologic scenarios to an economic framework for quantifying local and regional damages based on existing estimates of non‐market environmental values from the literature. The costs of lost wetland ecosystems, increases in particulate matter from exposed playa, and other local disamenities are substantial. For the scenarios considered, they range between approximately $500 million and $1 billion in present value (2019 USD). Estimated damages per acre‐foot (or thousand m3) of reallocated water exceed several thousand dollars. The majority arise from loss of wetland habitat; incremental particulate matter damages are relatively modest in our modeling but exacerbate salient air quality issues in the region. Interest in reallocating water from Imperial Valley, the largest user of Colorado River water, to other applications will increase over time. Our work highlights the importance of evaluating the impacts of such efforts.