Abstract. Resistivity, DC Hall effect and transverse magnetoresistance measurements were made on polycrystalline thin films of magnetite (Fe,OJ from 104 K to room temperature. The Verwey transition is observed at Tv = 123 K, about 4 K higher than reported for bulk magnetite. The ordinary and extraordinary Hall coefficients are negative over the entire temperature range, consistent with negatively charged carriers. The extraordinary Hall coefficient exhibits a dependence on the resistivity above Tv and a p2', dependence below Tv. The magnetoresistance is negative at all temperatures and for all magnetic field strengths. The planar Hall effect signal was below the sensitivity of the present experiment.

GaAs samples were implanted with tellurium at room temperature or at 150 °C and annealed to 750 °C with an SiO2 or Si3N4 protective layer. The highest electron concentrations and brightest photoluminescence were obtained for the hot implants with a Si3N4 protective layer.

Outdiffusion, lattice location and electrical behavior of Zn, Cd, Hg and Se, Te implanted into silicon at 50 keV were investigated by backscattering and channeling effect of 1 MeVHe+ ions and by Hall effect and sheet resistivity measurements. All the species exhibited outdiffusion with thermal processing. A significant fraction of Zn, Cd and Hg, when implanted into a substrate of 350°C, occupied regular interstitial lattice sites, while 50-60 per cent of the Se and Te atoms were on substitutional lattice sites. Selenium implanted at room temperature and mercury implanted into a substrate of 350°C exhibited depth dependent lattice location. The implanted layers showed n-type behavior: the maximum value of number of carriers/cmZ was less than the number of implanted ions/cm* in all cases. The highest electrical activity was observed for Se corresponding to 25 per cent of the substitutional component.

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A 128-bit multicomparator was designed to perform the search-sort function on arbitrary length data strings. Devices can be cascaded for longer block lengths or paralleled for bit-parallel, wordseriai applications. The circuit utilizes a 3-phase static-dynamic shift register cell for data handling and a unique gated EXCLUSIVE-NORcircuit to accomplish the compare function. The compare operation is performed bit parallel between a "data" register and a "key" register with a third "mask" register containing DON'T CARE bits that disable the comparator. The multicomparator was fabricated using p-channel silicongate metal-oxide-semiconductor (MOS) technolo~on a 107 X 150 mil chip containing 3350 devices. With transistor-transistor logic (TTL) input, data rates in excess of 2 MHr have been attained. The average power dissipation was 250 mW in the dynamic mode and 300 mW in the static mode.

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Hall and sheet-resistivity measurements as a function of temperature combined with layer removal have been used to study Si implanted with Teat energies up to 220 keY. At low doses c::S: 4 X l 0 12 em--'), Te has a donor level with a 140-meV activation energy. The activation energy decreases at higher Te doses and is approximately equal to zero forTe doses<: I 0 15 cm-2 • At high dose levels, the number of conduction electrons per unit area N, is more than an order of magnitude below the number of Te per unit area. High-temperature anneal treatments followed by quenching did not produce a substantial increase in N, , suggesting that the formation of Te clusters was not responsible for the low value of N, . Also, channeling measurements indicated a high substitutional fraction. Based on differential Hall measurements on samples implanted with phosphorus, with and without Si predamage, we conclude that residual radiation damage is not a major factor. A theoretical calculation, which includes the effect of decrease of activation energy with increasing impurity concentrations, indicated that the number of conduction electrons could be much less than the number of implanted Te even though the apparent activation energy is almost zero. Although the results of theoretical calculation do not give quantitative agreement with the experimental results, they do confirm the changes in apparent activation energy with concentration.