The Research And Detection Of MEMS Sensor Based On PHEMT Electromechanical Coupling Effect

At present, research on the electromechanical coupling effect of the FET and the M(N)EMS sensor whose sensitivity unit is FET has aroused the researchers'attention. But as the sensitivity unit of the electromechanical sensor, the MOSFET was chose mostly. Meanwhile, high electron mobility transistor(HEMT) as one of the FET, has widely applied in the communication because that it owns higher frequency, higher speed, lower yawp and higher power. HEMT is mostly used as the sensitivity unit of the gas sensor and the RF power sensor, and the research of MEMS accelerometer sensor based on the HEMT is few. Considering that the PHEMT (pseudomorphic-HEMT ) owns more higher concentration of the two-dimensitional electron gas(2DEG), the sensor mentioned in this paper use PHEMT as the sensitivity unit, and based on the research of the structure and electromechanical coupling effect of GaAs PHEMT, the detection method of the GaAs PHEMT mechanical sensitivity structure was studied systemically.This paper first introduces the I-V characteristic,transform characteristic and the electric character detected results of the GaAs PHEMT, and the result shows that the design of PHEMT is well and it also provides the data base for the matching detecting circle. In addition, by the rational test programme, the physical character and electromechanical character were detected. The mainly items shows as follow: by the detection and analyzing the temperature character of the GaAs PHEMT, I found that at the same drain voltage and gate voltage, the current between the drain and source became lower with the higher temperature; after detection the electromechanical character with the different work region for the PHEMT, the conclusion that the GaAs PHEMT owned the most visible electromechanical change could be got; through fixing the accelerometer on the vibration table, the vibration curve and the sensitivity of sensor could be obtained, its value is 0.137mV/g; by the frequency response detection, the perfect frequency segment for the signal of accelerometer could be got; finally, the equivalent piezoresistive coefficient of the accelerometer based on the GaAs PHEMT was detected and calculated, and its value is 0.72234649×10-9pa-1.The detection results show that the structure of the accelerometer based on the GaAs PHEMT is proper, the linearity is well, and at low-frequency, the sensitivity is stable. So, all of this availably validated the feasibility that the GaAs PHEMT is designed as the sensitive unit for force sensing sensor. These study productions make the foundation for lucubrate high sensitivity and high distinguishability MEMS accelerometer.