Since the beginning of the 1960s and up to the present time, laser ablation from metal surfaces under the action of short light pulses has been the topic of many researches. One of the first objects in the early ablation experiments presented thin metal films evaporated by radiation, which were used in lasers with nanosecond pulses as optical gates for Q-switching in resonators or for decoupling in amplifiers. Bleaching of the gates based on metal layers with a time constant τt ≈ 10−8 s observed in a number of experiments, was usually considered as a result of a simple evaporation of matter. We analyze the data of the experiments with a mylar tape [≈0.05 µm aluminum (Al) layer on ≈20 µm lavsan substrate] used as a gate for optical isolation in one of the first Nd: glass laser facilities with a power of ≈1 GW. That gate was irradiated by pulses of Q-switched oscillators: pulse duration 10−7–10−8 s, intensity 107–108 W/cm2. A jump in the transmittance of the expanding Al layer was registered (from ≈0.1 to 50% at τt ≈ 10−9 s). The present study shows that one should consider the metal–insulator phase transition in a superheated liquid metal layer as the mechanism of the fast (up to 10–10–10–11 s) increase in the transmittance of the Al film gate at nanosecond-pulsed laser ablation.

We explore some aspects of the optimization of amorphous semiconductors as well as low- and high-dielectric-constant (low-/high-k) materials viewed purely from the perspective of percolation and topological constraint theories. We specifically illustrate how percolation, constraint theory, and mean network coordination, 〈r〉, play underlying roles in determining the electrical and mechanical properties of amorphous semiconducting and dielectric materials as well as interfaces that are important for modern micro-/nanoelectronic devices.

Mechanisms leading to correlation between structural phase transitions in functional oxides and consequent insulator–metal transitions driven by band gap closure are an active area of research. In cases where large volume changes are present, structural stability considerations become important. Here, we present in situ studies of mechanical instability of VO2 grown on self-supported Si3N4 membranes spanning the structural phase transition boundary of vanadium dioxide. We observe film cracking across the phase transition, and the transition-induced cracks correlate with the symmetry change and the corresponding changes in the optical/electrical response arising from the insulator–metal transition. Transmission electron microscopy studies revealed twinned platelets proximal to crack regions. Interestingly, the membranes are mechanically stable until a large fraction of resistance change occurs across the phase transition. The ability to manipulate the stability and controlled rupture of self-supported membranes through temperature or other stimuli could be of interest to microelectromechanical systems and sensor devices.

We report controlled modifications in the semiconductor-to-metal transition characteristics of VO2 single-crystal thin films induced by swift heavy ion (SHI) irradiation with varying ion fluences. At very high energies of ions (200 MeV Au), the electronic stopping (∼2009 eV/Å) dominates over nuclear stopping (∼16 eV/Å). Under these extreme electronic excitation conditions caused by electronic stopping and the passage of SHIs through the entire thickness of the film, creation of certain unique type of defects and disordered regions occurs. X-ray diffraction, Raman spectroscopy, infrared transmission spectroscopy, x-ray photoelectron spectroscopy (XPS), and electrical measurements were performed to investigate the characteristics and role of these defects on structural, optical, and electrical properties of VO2 thin films. XPS and electrical resistivity measurements suggest that the ion irradiation induces localized defect states that appear to correlate well with the creation of disordered regions in the VO2 thin films. The high-energy heavy-ion irradiation changes the transition characteristics drastically from a first-order to a second-order transition (electronic—Mott type). The low-temperature conductance data for these ion-irradiated films fit well with the quasiamorphous model for resistivity of VO2, where ion irradiation is believed to create mid-bandgap defect states.

We report on in situ stress relaxation behavior of vanadium dioxide thin films across the thermally driven metal–insulator transition (MIT) and size effects. Although the residual stress follows an inverse relationship with film thickness, the metal–insulator phase transition-induced stress varies nonmonotonically with increase in film thickness and grain size. Maximum transformation stress of −447 MPa is observed across the MIT for ∼170-nm-thick film with an average grain size of ∼70 nm. The interplay between constraint effects and nanostructure leads to nontrivial stress relaxation trends and provides insights into design of phase transition materials for switching devices.