A semiconductor laser whose cavities are “self-formed” due to strong optical scattering in highly disordered gain media is demonstrated. The lasers are made of zinc oxide polycrystalline films grown on amorphous fused silica substrates. Lasing occurs at an ultraviolet wavelength of ∼380 nm under optical pumping. Actual images of the microscopic laser cavities formed by multiple scattering have been captured. These results suggest the possibility of using disordered semiconductor microstructures as alternative sources of coherent light emission.

In this study, the excellent energy storage performance is achieved by constructing opposite double-heterojunction ferroelectricity-insulator-ferroelectricity configuration. The PbZr 0.52 Ti 0.48 O 3 films and Al 2 O 3 films are chosen as the ferroelectricity and insulator, respectively. The microstructures, polarization behaviors, breakdown strength, leakage current density, and energy storage performance are investigated systematically of the constructed PbZr 0.52 Ti 0.48 O 3 /Al 2 O 3 /PbZr 0.52 Ti 0.48 O 3 opposite double-heterojunction. The ultrahigh electric field breakdown strength (≈5711 kV cm −1 ) is obtained, which is beneficial to achieve high energy storage density. Meanwhile, the high linearity of hysteresis loops with low energy dissipation is obtained at a proper annealing temperature, which is induced by partially crystallized and is in favor of achieving high energy storage efficiency η. The PbZr 0.52 Ti 0.48 O 3 / Al 2 O 3 /PbZr 0.52 Ti 0.48 O 3 annealed at 550 °C exhibits excellent energy storage performance with a storage density of 63.7 J cm −3 and efficiency of 81.3%, which is ascribed to the synergetic effect of electric breakdown strength (E BDS = 5711 kV cm −1 ) and the polarization (P m -P r = 23.74 µC cm −2 ). The proposed method in this study opens a new door to improve the energy storage performance of inorganic ferroelectric capacitors. Keywords breakdown strength, energy storage, heterojunctions, polarization behavior

BiFeO 3 / Nb – SrTiO 3 heterojunctions with room-temperature resistance switching (RS) and white-light photovoltaic (PV) effects were fabricated by pulsed laser deposition. The current-voltage characteristics of these heterojunctions show a good rectifying property with a large rectifying ratio of 104. Nonvolatile bipolar RS effect was observed with an ON/OFF-state current ratio of about 102. The heterojunctions also exhibit a substantial white-light PV effect. Both the RS and PV behaviors can be modulated by additional pulsed voltages, which control the electric polarization of the heterojunctions. This letter is helpful for exploring the multifunctional heterojunctions and their applications in memory devices and solar cells.

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