Papers by Author: Hui Juan Fan

Abstract: We report on a novel method for measurement of the strain in microcantilever, and a contactless measurement system for strain in microcantilever is designed and implemented based on position sensitive detector (PSD) using optical lever method. To verify the validity and accuracy of the results from measurement, a finite element model of the uniform strength microcantilever has been developed to simulate mechanical behavior in microcantilever based on finite element method (FEM). The results show that results obtained from FEM and measurement based on PSD show excellent agreement. This work has provided a novel and more effective method for measurement of the strain in microcantilever.

Abstract: In this paper a twin-island structure in piezoresistive pressure sensor based on MEMS technology has been presented, and a finite element mechanical model has been developed to simulate the static mechanical behavior of this twin-island structure sensor chip, especially the stress distributions in diaphragm of the sensor chip, which has a vital significance on piezoresistive pressure sensors’ sensitivity. The possible impacts of twin-island’s location and twin-island’s width on the stress distributions, as well as the maximum value of compressive stress and tensile stress, have been investigated based on numerical simulation with Finite Element Method (FEM). The simulation results show that twin-island’s location has great effect on the stress distributions in sensor chips’ diaphragms and the sensitivity of piezoresistive pressure sensors, compared with the twin-island’s width.

Abstract: Hydrogenated nanocrystalline silicon (nc-Si:H) films were deposited on glass substrates using Radio frequency plasma-enhanced chemical vapor deposition(RF-PECVD)from a B2H6/SiH4/H2 gas mixtures. In this paper, we mainly changed the Borane-Silane flow rate ratio (β), while other parameters were kept constant. Raman spectrum and X-ray diffraction were employed to investigate the micro-structure of the films, and the indentations were used to measure the mechanical characters (the Young’s modulus (E) and hardness (H)). The Raman spectrum showed that, withβincreasing the crystalline fraction decreased, which indicated that more boron doped might not be propitious to the formation of crystalline of the thin films. XRD spectrum revealed that the films have a remarkably preferential orientation. The analysis of the Young’s modulus and hardness by TriboIndenter nano system suggested that the increase inβhad concernful effects in the decrease of E and H values, so we can control the mechanical characters of the thin films by means of changing the doped concentrations. In view of these results, it may be concluded that the use of lowβconditions might lead to growth of nc-Si:H films with high crystallinity, and as well high Young’s modulus and hardness.