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We carry out an In0.53Ga0.47As/In0.52Al0.48As single photon avalanche diode which exhibits a single photon detection efficiency exceeding 60% at 1310 nm and neat temporal characteristic of 65 ps. A novel concept of dual multiplication layer is incorporated to avoid the tradeoff between dark count rate, afterpulsing and timing jitter, paving the possibility to improve the overall performance of a single photon detector. Based on this elevated device structure, we further optimize the detection efficiency and timing jitter by employing a delicate mesa structure to better confine the electric field distribution within the central multiplication region. For our detector operated under gated mode, a shorten gate width together with an increase of excess bias percentage leads to a significant improvement in the detection performance. We eventually achieve a single photon detection efficiency of 61.4% without the involvement of afterpulsing at the gating frequency of 10 kHz for 200 K.

The performance of InGaAs/InAlAs single photon avalanche diodes (SPAD) was improved with fabrication in triple mesa. Current SPADs achieve better dark count rate of 5 × 104 ⁄2 for single photon detection efficiency of 31% at RT.

Olivine compounds LiAlxFe1−3x/2PO4/C [x=0, 0.01, 0.02, 0.04, 0.06, 0.12] were prepared via an easy solution method and electrochemical properties were examined by means of X-ray diffraction, cyclic voltammetry, and charge–discharge tests. The results indicate that Al3+ does not affect the olivine structure of the cathode but considerably improves its initial capacity and cycle performance. Among the Al3+-substitution powders, LiAl0.01Fe0.985PO4/C shows the best electrochemical performance. It shows initial specific discharge capacities of 157.67 and 126.65 mA hg−1 with C rates of 0.5 C and 5 C, respectively, which is ascribed to the enhancement of the electronic conductivity by Al3+-substitution and carbon coating.