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CoFeB thin films and magnetic tunnel junctions using them are studied for magnetostriction effect. The single layer films were sputter deposited with excellent soft magnetic properties including a high saturation magnetization of 1.5 T, a near zero hard axis coercivity, a low easy axis coercivity of 2.0 Oe, and an induced magnetic anisotropy field of 32 Oe. The saturation magnetostriction constant is measured to be 31 ppm.Magnetic tunnel junctions (MTJ) were fabricated and tested for potential strain gauge applications. The gauge factor for the magnetostrictive MTJs, a measure of strain sensitivity, is many times of the best piezoresistive devices.

An experimental study has been made of the energy level structure of a phosphorus donor impurity in silicon, using Hall coefficient and Hall mobility measurements on six samples of widely varying impurity content and compensation. The main purpose was to test the Kohn-Luttinger theoretical model which predicts a splitting of the sixfold degenerate (excluding spin) ground "Is" level, with a single state being depressed in energy by between 0.009 and 0.015 ev relative to the remaining fivefold degenerate level. The splitting energy can be measured by comparing carrier concentration vs temperature curves corresponding to this energy level scheme with experimental curves derived from Hall data. The curves for our samples all agree well with the Kohn-Luttinger model for splitting energies of between 0.009 and 0.012 ev, in agreement with the theoretical prediction.

Feasibility of fabricating low power, high-speed, magnetoresistive signal isolators employing linear spin-valve resistors as sensing elements has been demonstrated. In the fabricated prototype digital isolators, linear spin-valve resistors are physically isolated from an on-chip coil by an 11 m BCB isolation barrier, which provides the galvanic isolation with a breakdown voltage larger than 2000 V. The devices are high speed ͑Ͼ50 MHz͒, small size, and low power consumption. Only a 4.5 mA coil driving current is required for the device to be fully functional. The power consumption is estimated to be ϳ1/6 of NVE's present isolator products, which requires a 50 mA coil driving current. Besides digital signal isolators, linear spin-valve resistors can also be used in analog signal isolators. The response of the linear spin-valve resistors to the current passing through the coil has been demonstrated to have a very good linearity, with a linearity error less than 0.05%.

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