An Mw 9.3 earthquake originated in the Indian Ocean off the western coast of northern Sumatra at 00:58:53 Universal Time (UT) on 26 December 2004. Two giant ionospheric disturbances at 01:19 and 04:10 UT are observed by a network of digital Doppler sounders in Taiwan. The first disturbance excited mainly by Rayleigh waves, which consists of a packet of short‐period Doppler shift variations, results in vertical ionospheric fluctuations with a maximum velocity of about 70 m/s and displacement of about 200 m. The second disturbance, in a W‐shaped pulse propagating at a horizontal speed of 360 ± 70 m/s, is attributable to coupling of the atmospheric gravity waves (AGW) excited by broad crustal uplift together with the following big tsunami waves around the earthquake source zone. The accompanying ionosonde data suggest that the AGW in the atmosphere may have caused the ionosphere to move up and down by about 40 km.

We present detailed experimental results of the temperature dependence of continuous wave and time-resolved photoluminescence ͑PL͒ spectroscopy in self-assembled InAs/GaAs quantum dot and quantum ring nanostructures. A dramatic increase in PL decay time of the excited and ground states is observed in InAs quantum rings at high temperature. We speculate that the longer PL lifetime in quantum rings is due to the interplay among the dark states, ground states, and the reduced wave function overlapping between electrons and holes. A rate equation model is proposed to interpret the observed temperature dependence of the ground state exciton lifetime.

A voltage-tunable multicolor triple-coupled quantum-well infrared photodetector (TC-QWIP) has been developed for 8–12 μm detection. The TC-QWIP consists of three coupled quantum wells formed by an enlarged Si-doped InxGa1−xAs quantum well and two undoped GaAs quantum wells separated by two thin AlyGa1−yAs barriers. Two TC-QWIP structures with varying indium and aluminum compositions were designed and demonstrated. Due to the strong coupling effect of the asymmetrical quantum wells, three bound states (E1, E2, E3) are formed inside the quantum wells of the TC-QWIP. The main detection peak wavelength is due to E1→E3 bound states transition for both devices, while two secondary detection peaks due to E1→E2 and E1→Ec continuum states transitions under different biases were also observed. In addition, a strong quantum-confined Stark shift effect for the E1→E3 transition was observed in the wavelength range of 8.2–9.1 and 10.8–11.5 μm for QWIP-A and QWIP-B, respectively; both devices exhibit a linear dependence of detection peak wavelength on the applied bias voltage. A spectral responsivity of Ri=0.05 A/W and background limited performance (BLIP) detectivity DBLIP*=6.1×109 cm√Hz/W were obtained at Vb=5 V, λp=8.6 μm, and TBLIP=66 K for QWIP-A, while Ri=0.33 A/W and DBLIP* =1.63×1010 cm√Hz/W at Vb=4 V, λp=11.2 μm, and TBLIP=50 K were obtained for QWIP-B.

PSS is used as a hole-transporting conducting layer for hybrid cells.

Articles you may be interested inDeep levels in GaAs(001)/InAs/InGaAs/GaAs self-assembled quantum dot structures and their effect on quantum dot devices J. Appl. Phys. 107, 073111 (2010); 10.1063/1.3359704Combined optical and electrical studies of the effects of annealing on the intrinsic states and deep levels in a self-assembled InAs quantum-dot structure