Papers by Author: Ji Jun Xiong

Abstract: In this paper, We use a novel principle to detect acceleration and report how I-V characteristics and piezoresistance coefficient of AlGaN/GaN HEFT-micro-accelerometer are affected by setting different temperatures. It is shown that saturation current of device would go down if the temperature goes up, which is about 0.028mA/°C, based on the research. However, the device can work well at the temperature range of -50°C to 50°C, which indicates that it can work safely in the larger temperature range.

Abstract: A novel MEMS vector hydrophone with bionics structure was introduced in 2007. As the acoustic-electric transducer infrastructure and the acoustic package of hydrophone have been optimized, the performance of the hydrophone has been greatly improved compared with the previous. This hydrophone calibration was finished in National Defense Underwater Acoustics Calibration Laboratory of China. According to the test results, the sensitivity of the hydrophone is -165dB（including pre-amplification 20 dB）, the frequency response ranges from 20Hz to 2kHz (±5dB). And this hydrophone has a good directional pattern in the form of "8"-shape.

Abstract: In the paper, the principle, the preparation and the performance of the dual-color infrared HgCdTe detector is introduced. The detector is a combination of different wave band filter and different respond wave band element. The application of the dual-color infrared HgCdTe sensitive element for methane gas detection sensor is developed. A two-element HgCdTe methane detector which responds between 3.13~3.53μm and 3.91~4.09μm wave bands respectively was reported. The performance of each detection channel was presented. The experiment test and analyze are fulfilled. The experiment result indicates that under the refrigeration temperature the dual-color HgCdTe detector not only has a favorable response ability and repetition but also can realize the response and distinguish ability to methane gas through integrate narrow band filter on the front of the detector sensitive element.

Abstract: Based on the photo ionization principle, a gas sensor for the hydrazine is designed. The photo ionization gas sensor can also measure other volatile organic compounds and other gases in concentrations from sub parts per billion to 10000 parts per million (ppm). This gas sensor is the most efficient and inexpensive type of gas sensor. They are capable of giving real-time readings and monitoring continuously. The design of micro ionization chamber, signal detection circuits and installation technology is expatiated in detail. Through researching the design of cell structure, the cell with integration and miniaturization has been devised. By taking Single-Chip Microcomputer (SCM) as intelligence handling, the functional block diagram of gas detection system is designed with the analyzing and devising of its hardware and software system. Experiment results show that the gas sensor has reached the technology requirement of portable, mini-volume, high accuracy, fast response, continuous test, and is able to apply in detecting the organic gases. Therefore, the photo ionization sensor has a promising future for the hydrazines gas and volatile organic compounds detection.

Abstract: Planar Microtoroid cavities have important application in many researching and application domains due to their ultrahigh quality factor (Q). But the special toroid structure can not be fabricated through traditional technology. In this paper, a novel processing method for fabricating microtoroid cavities using high-power CO2 laser after a series of traditional processing steps is introduced. The processing details are discussed including light path, focusing system and other important parameters. Test using scanning electronic microscope and laser-Raman spectrum shows that fabrication of planar microtoroid cavity using CO2 laser is feasible. The final microtoroid cavity is fabricated with slight impact to the silicon strut-beam, ensuring excellent optical performance in Planar Microtoroid cavity.

Abstract: A trench is used as a storage capacitor in dynamic memory (DRAM) technologies (deep storage trenches), or as an isolation structure in CMOS, bipolar and BiCMOS technologies. But a shallow trench structure has also been shown to be a major factor in substrate defect generation during processing. Such defect generation is directly related to mechanical stresses existing around the trench. This stress can be monitored, using Raman spectroscopy, to a stress resolution of 10MPa and a spatial resolution of 0.2μm. In this paper, a trench structure is designed and fabricated, and the test results for local stresses within the trench are shown to be in good correspondence with theory.

Abstract: Meso- piezoresistive effect is proposed, which is defined as “Strain Tuning of the resonant current”, in order to convert a weak mechanical signal into a strong tunneling current signal. If a mechanical signal is acted on an related mechanical nano-structure, the corresponding strain distribution will be produced in the structure; the built- in electric field will be resulted from the strain in system in some conditions; the strain and built-in electric filed will result in the change of electronic energy states; the change of electronic energy state will influence on the value of the tunneling current. Two experimental units are designed, one being used to detect an acoustic signal under sea, other to detect acceleration.