In this work, the detection ability of nanosensors can be improved extraordinary by surface defects engineering. The kinked SnO 2-X /SnO 2 nanostructure was fabricated by tuning the oxygen flow and used this kinked SnO 2-X /SnO 2 nanostructure to study the mechanism of surface defect (oxygen vacancy, V O ) affection through the electric measurement. For UV light sensing, the response of SnO 2-X NW device is always better than SnO 2 NW device, two orders higher under pure O 2 surrounding condition. The detection mechanism can be clarified by changing the detection environment (oxygen concentration) and the UV light detection sensitivity can be improved by increasing the surface V O density. Furthermore, the SnO 2-X NW device is very sensitive to its surrounding environment due to the high surface V O density. Hence, the CO/O 2 alternate-detection was used to verify our hypothesis; the results show that the SnO 2-X NW device presents great detection ability, compared with SnO 2 NW device. The sensitivity of SnO 2-X NW device is two order enhancements and the reset/response time is faster, compared with SnO 2 NW device. To verify this hypothesis, the polycrystalline structure was fabricated to prove that the detection ability of metal-oxide nanosensors can be improved gigantically by increasing surface defect amount.
A low-power K-band CMOS current-mode up-conversion mixer is proposed. The proposed mixer is realized using four analog current-squaring circuits. This current-mode up-conversion mixer is fabricated in 0.13-μm 1P8M triple-well CMOS process, and has the measured power conversion gain of −5 dB. The fabricated CMOS up-conversion mixer dissipates only 3.1 mW from a 1-V supply voltage. The VCO can be tuned from 20.8 GHz to 22.7 GHz. Its phase noise is −108 dBc/Hz at 10-MHz offset frequency. It is shown that the proposed mixer has great potential for low-voltage and low-power CMOS transmitter front-ends in advanced nano-CMOS technologies.
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