Repetitive transcranial magnetic stimulation (rTMS), defined as the administration of a series of magnetic stimuli to the brain for the purpose of altering brain function, is an experimental medical intervention. rTMS currently is used to probe various aspects of brain function in the context of research studies approved by local ethics committees. rTMS also is under investigation as a potential treatment for various neurologic and psychiatric disorders. In light of the growing interest in using rTMS in a variety of experimental and therapeutic settings, the International Society for Transcranial Stimulation has recognized the need to formulate a consensus statement to assist the field in developing guidelines for its safe application. Whether the intended use is experimental or therapeutic, certain principles regarding the safety of rTMS apply. This statement is not aimed at guiding the therapeutic use of rTMS in any given condition or its application in any research paradigm, but rather is meant to apply broadly wherever rTMS is used.

rTMS has significant risks, most importantly that of producing epileptic seizures. The degree of risk varies with the dosing parameters and individual subject factors. Therefore, rTMS should be administered only under a licensed physician's orders (ie, by prescription or through some other mechanism that makes a physician directly responsible for its administration to the individual patient or research subject). Because rTMS has potential behavior-changing effects, undesirable side effects, and therapeutic impact, careful assessment of the risk and appropriateness of rTMS in each clinical or scientific context is critical and can only be made by, or in consultation with, a physician knowledgeable and experienced in the use of rTMS and fully trained in neurology, psychiatry, or another appropriate specialty.

We report on a direct epitaxial growth approach for the heterogeneous integration of high speed III-V devices with Si CMOS logic on a common Si substrate. InP-based heterojunction bipolar transistor (HBTs) structures were successfully grown on patterned Si-on-Lattice-Engineered-Substrate (SOLES) substrates using molecular beam epitaxy. DC and RF performance similar to those grown on lattice-matched InP were achieved in growth windows as small as 15×15μm2. This truly planar approach allows tight device placement with InP-HBTs to Si CMOS transistors separation as small as 2.5 μm, and the use of standard wafer level multilayer interconnects. A high speed, low power dissipation differential amplifier was designed and fabricated, demonstrating the feasibility of using this approach for high performance mixed signal circuits such as ADCs and DACs.

Due to the prohibitively high 4.1% lattice mismatch, direct growth of GaAs on Si invariably leads to very high dislocation densities (> 108/cm2) which have precluded its use in device applications despite numerous attempts. However, the growth of low threading dislocation density (∼2 × 106/cm2) relaxed graded Ge/GexSi1−x/Si heterostructures can bridge the gap between lattice constants by replacing the high mismatch GaAs/Si interface with a low mismatch (< 0.1%) GaAs/Ge interface. Although the lattice mismatch problem is thus eliminated, the heterovalent GaAs/Ge interface remains highly susceptible to antiphase disorder. Since antiphase boundaries (APBs) nucleated at the GaAs/Ge interface act as scattering and nonradiative recombination centers, growth of device quality GaAs on Ge/GexSi1−x/Si demands effective suppression of antiphase disorder. The current work investigates the sublattice location of GaAs on 6° offcut (001) Ge/GexSi1−x/Si substrates as a function of atmospheric pressure metal-organic chemical vapor deposition (MOCVD) growth initiation parameters. Two distinct GaAs phases are observed, one dominant at temperatures > 600°C and another at temperatures <500°C. Incomplete phase transitions during pre-growth thermal cycling account for the appearance of localized bands of anti-phase disorder where the polarity of the GaAs film switches. We suspect that background arsenic levels in the MOCVD system are largely responsible for inducing the observed phase transitions. The complete suppression of antiphase disorder under optimized growth conditions is demonstrated by transmission electron microscopy (TEM)