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The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers (VCSELs), in which the proton implanted depth and profile are main parameters. Threshold characteristics of VCSELs with various proton implanted depths are studied after optical, electrical and thermal fields have been simulated self-consistently in three dimensions. It is found that for VCSELs with confinement radius of 2 μm, increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region. Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs. The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 μm, while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors (DBRs) and confinement radius of 2.5 μm can realize the minimum temperature.

Chaos transited from period doubling in plasmas is characterized with several methods. Waveform and fast Fourier transform confirm that the signal is nonperiodic. One dimensional unimodal like structures of the return maps of next amplitude with peak and valley values are obtained to illustrate the deterministic feature. Numerical experiments on one-dimensional logistic map are carried out to simulate the experimental results. Positive Lyapunov exponent 1.33±0.10, directly calculated from the experimental data, provides the evidence that the signal is chaotic. Correlation dimension 2.75±0.05 demonstrates that this signal is decreased to a low dimensional attractor in the plasma.

Polycrystalline Bi0.975La0.025Fe0.975Ni0.025O3 (BLFNO) film is fabricated on Pt/Ti/SiO2/Si(111) substrate by sol–gel method. It is found that the well-crystallized BLFNO film is polycrystalline, and the Pt/BLFNO/Pt capacitor possesses good ferroelectric properties with remnant polarization of 74 μC/cm2 at electric field of 833 kV/cm. Moreover, it is also found that the leakage current density of the Pt/BLFNO/Pt capacitor increases with the increase of measurement temperature ranging from 100 to 300 K. The leakage density of the Pt/BLFNO/Pt capacitor satisfies space-charge-limited conduction (SCLC) at higher electric field and shows little dependence on voltage polarity and temperature, but shows polarity and temperature dependence at lower applied electric field. With temperature increasing from 100 to 300 K at lower applied electric field, the most likely conduction mechanism is from Ohmic behavior to SCLC for positive biases, but no clear dominant mechanism for negative biases is shown.