Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

We show that the two-photon nonresonant contributions to the lifetime of excited 3s and 3d states of hydrogen, as given by a formula recently derived by Cresser et al. [Phys. Rev. A 33, 1677 (19S6)],can be evaluated in an economic way using the analytic expressions of the amplitudes of 3s-1s and 3d-1s two-photon transitions. Our numerical evaluation confirms the numbers given by Cresser et al. In a recent paper Cresser et al. ' have considered the contribution of two-photon emission to the lifetime of an excited state which can also decay by one-photon emission. Using time-dependent perturbation theory up to fourth order and Markov approximation, they have separated in the reciprocal of the lifetime of an initial state I i ) two contributions [Eq. (Ig) of Ref. I], I (1)+ I (2) 0& --E; -%co&, and interchanging the polarization vectors 2 2and e2. m, is the electron mass, co& and co2 the two photon frequencies connected by %co, +fico2 --E, -E, . We refer in the following to an initial state with n; =3 and defined orbital momentum l; (0 or 2). We complete XI and Xz with the contribution of the intermediate 2p and 3p states, obtaining in the case of X & with I ', " the spontaneous decay rate of the state I i ) due to one-photon emission, and I', ' the contribution of nonresonant intermediate transitions to all the states of energy higher than the initial-state energy E;. In Ref. 1

The phenomenon of resistive switching (RS), which was initially linked to non-volatile resistive memory applications, has recently also been associated with the concept of memristors, whose adjustable multilevel resistance characteristics open up unforeseen perspectives in cognitive computing. Herein, we demonstrate that the resistance states of LixCoO2 thin film-based metal-insulator-metal (MIM) solid-state cells can be tuned by sequential programming voltage pulses, and that these resistance states are dramatically dependent on the pulses input rate, hence emulating biological synapse plasticity. In addition, we identify the underlying electrochemical processes of RS in our MIM cells, which also reveal a nanobattery-like behavior, leading to the generation of electrical signals that bring an unprecedented new dimension to the connection between memristors and neuromorphic systems. Therefore, these LixCoO2-based MIM devices allow for a combination of possibilities, offering new perspectives of usage in nanoelectronics and bio-inspired neuromorphic circuits.

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