Key Engineering Materials Vol. 503

Abstract: Boron-doped nanocrystalline silicon thin films(p-nc-Si:H) were deposited on glass substrates by plasma enhanced chemical vapour deposition (PECVD) using SiH₄ / H₂ / B₂H₆. The effects of substrate temperature, rf power and diborane flow on the microstructure, the electrical properties of nanocrystalline silicon thin films have been investigated. The results show that, increasing substrate temperature, rf power and B₂H₆ flow can improve the conductivity of P-Si thin film. However, exceeding one value, they are not advantageous to improve the conductivity due to the decrystallization of films. Hence, appropriate process conditions are crucial for the preparation of high quality p layer. crystalline volume fraction (Xc) 26.2 %, mean grain size (d) 3.5nm and conductivity 0.374S/cm, p-nc-Si:H thin film was deposited.

Abstract: The Modular Platform System in this Paper Consists of a Series of Modularized MEMS Subsystems, Including Central Control Unit, MEMS Attitude Measurement Unit, Environment Unit, Flight Measurement and Control Unit, Time Control Unit, Impact Vibration Measurement Unit and other Auxiliary Modular Units. the Key of the System Is the MEMS Attitude Measurement Unit, which Can Resolve the Real Time Attitude Information of the Carrier. the System Platform Chooses Different Sensors and Units According to Various Circumstances and Implements Data Collection, Fusion and Solution through the Central Processing Module. by Means of Carrying Distinct Units, System Platform Can Constitute many Measurement Control Systems, such as Micro Wireless Attitude Determination System, MAV Flight Data Recorder, MAV Flight Control System and PHM (prognostic and Health Management). with Application of MEMS, the System in this Paper Is High-Efficient, Low-Weighted, Simple-Structured, High-Reliable and even Can Respond in a Short Time. in View of these Merits, the System Can Be Applied in many Kinds of Attitude Measurement and Control System.

Abstract: The characteristics of several package structures of high power white Light emitting diode (LED) are described in this paper. The influence of different structures on thermal properties is analyzed. Forward voltage method is used to test the thermal resistance of LED chips.

Abstract: In order to give consideration to the speed and distance of data transmission, we design and put forward a design of ethernet interface based on FPGA and W5300, in which we achieve the high-speed ethernet connectivity between equipment and terminal device. UDP unicast mode is adopted in ethernet interface, and high-quality transmission medium is used to ensure the reliability of transmission link. It is proved that, the interface, with characteristics of relatively high-speed and long-distance, is relatively reliable and almost no package lost.

Abstract: A semi-continuum approach is developed for mechanical analysis of a silicon nanobeam, which captures the atomistic physics and retains the efficiency of continuum models. Young’s modulus of the silicon (001) nanobeam along [100] direction is obtained by the developed semi-continuum approach, which decreases dramatically as the size of a silicon nanobeam width and thickness scaling down. Taking into account the variations of Young’s modulus at different size, the load properties of the nanobeam is computed. The model predicts the deflection of the nanobeam is size-dependence. Introduction

Abstract: This paper describes a meteorological detection system integrating a variety of micro-sensors. Carried by shrapnel, this system is adaptable to complex environment and can gather long-range meteorological information of the region concerned. Basic work process is as follow, the information acquisition module is delivered by shrapnel to the designated area. In the process of falling, meteorology, location and time data is obtained through the micro-sensors and GPS receiver. After analyzing and calculating by the Micro Control Unit, the information received will be transmitted to the user terminal by wireless transmission module. Thus the information collection is completed. The use of micro-sensor makes this system compact, stable and less energy consumption, so the system is worth high practical value.

Abstract: In this paper, a design of a digital decimation filter which has a output of 24 bits for high-precision 4-ordes Σ-Δ ADC is proposed. The digital decimation filter includes a CIC filter, a compensation filter and a half band filter. The over-sampling rate of the digital decimation filter is 256, the cutoff frequency is 1kHz, the coefficient of the pass-band ripple is -0.25dB, the stop-band attenuation is -162dB, simulation results using Matlab and modelsim are correct, the result of the FPGA verification shows that the design meet the requirement of the high-precision 4-ordes Σ-Δ ADC.

Abstract: DNA charged negatively could be transported through a solid nanopore by the force of an electrical field. Recently, the nice properties of graphene attract a lot of researchers. In this paper, A single graphene membrane was punched to form a nanopore and a ds-DNA was driven to pass through the pore by all-atom molecular dynamics simulations. The single graphene membrane was demonstrated useful in DNA sequencing. It suggested that the velocity of DNA translocating through a single graphene pore could be controlled by adjusting the appropriate voltage and the diameter of the nanopore.

Abstract: A non-enzymatic glucose sensor based on nano-gold modified Ag electrode was fabricated by two steps. Gold colloid were firstly prepared according to the literature[11] and then a carefully cleaned Ag electrode was dipped into the gold colloid to obtain the non-enzymatic glucose sensor. The structures and morphologies of nano-gold colloid and nano-Au modified electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis absorption spectra. The direct electrocatalytic oxidation of glucose in alkaline medium at this modified electrode has been investigated in detail. The result showed that the nano-gold modified electrode had good current response to glucose. The oxidation current was linearly related to the concentration of glucose range frome 0.2 to 175.2μmol/L with a detection limit of 29.5 nmol/L. The nano-gold modified electrode allows highly sensitive, low working potential, fast amperometric sensing of glucose, thus is promising for the future development of non-enzymatic glucose sensors.

Abstract: With the development of MEMS technology, the pressure sensors, one of mature MEMS devices, are expected to better performance. In order to improve sensors performance, supporting vitreous body shape is elongated and thinned. But the variety of the vitreous body shape brings the new difficulties for anodic bonding between the vitreous body and the silicon during the sensors production, and causes that the common bonding process conditions are unavailable and bonding failure rate dramatically increases. Therefore, this article analyzes the bonding process between slender vitreous body and silicon, and researches on the influence of the vitreous body variety on the pressure, temperature and voltage. The results showed that the bonding is the best when the cantilever elastic deformation is less than 0.5mm, interface temperature loaded from the silicon is 415°C and the voltage 1200V is loaded from the position near H=2mm.