Haisheng San

Design and simulation of GaN based Schottky betavoltaic nuclear micro-battery

The current paper presents a theoretical analysis of Ni-63 nuclear micro-battery based on a wide-band gap semiconductor GaN thin-film covered with thin Ni/Au films to form Schottky barrier for carrier separation. The total energy deposition in GaN was calculated using Monte Carlo methods by taking into account the full beta spectral energy, which provided an optimal design on Schottky barrier width. The calculated results show that an 8 μm thick Schottky barrier can collect about 95% of the incident beta particle energy. Considering the actual limitations of current GaN growth technique, a Fe-doped compensation technique by MOCVD method can be used to realize the n-type GaN with a carrier concentration of 1×10(15) cm(-3), by which a GaN based Schottky betavoltaic micro-battery can achieve an energy conversion efficiency of 2.25% based on the theoretical calculations of semiconductor device physics.

A high open-circuit voltage gallium nitride betavoltaic microbattery

A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p?i?n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5?mCi, the open-circuit voltage of the fabricated microbattery with 2???2?mm2?area reaches as much as 1.64?V, which is the record value reported for betavoltaic batteries with 63Ni source, the short-circuit current was measured as 568 pA and the conversion effective of 0.98% was obtained. The experimental results suggest that GaN is a high-potential candidate for developing the betavoltaic microbattery.

Wireless passive polymer-derived SiCN ceramic sensor with integrated resonator/antenna

This paper presents a passive wireless polymer-derived silicon carbonitride (SiCN) ceramic sensor based on cavity radio frequency resonator together with integrated slot antenna. The effect of the cavity sensor dimensions on the Q-factor and resonant frequency is investigated by numerical simulation. A sensor with optimal dimensions is designed and fabricated. It is demonstrated that the sensor signal can be wirelessly detected at distances up to 20u2009mm. Given the high-temperature stability of the SiCN, the sensor is very promising for high-temperature wireless sensing applications.

Design and simulation of betavoltaic battery using large-grain polysilicon

In this paper, we present the design and simulation of a p-n junction betavoltaic battery based on large-grain polysilicon. By the Monte Carlo simulation, the average penetration depth were obtained, according to which the optimal depletion region width was designed. The carriers transport model of large-grain polysilicon is used to determine the diffusion length of minority carrier. By optimizing the doping concentration, the maximum power conversion efficiency can be achieved to be 0.90% with a 10 mCi/cm(2) Ni-63 source radiation.

Self-Packaging Fabrication of Silicon–Glass-Based Piezoresistive Pressure Sensor

A self-packaged piezoresistive pressure sensor was fabricated using a silicon-glass anodic bonding technique. The Wheatstone bridge piezoresistive sensing configuration was located on the lower surface of the silicon diaphragm and was vacuum sealed in a Si-glass cavity, and the embedded Al feedthrough lines at the Si-glass interface were used to realize the electrical connections between the piezoresistive sensing elements and hybrid metal electrode pads through Al vias and heavily doped diffusion zones. The pressure sensors demonstrate comparable performance characteristics, but a more simple process and low cost in comparison with the commercial Si-based piezoresistive pressure sensor. Due to the self-packaging protection, the pressure sensors are capable of handling harsh environments.

Silicon-glass-based single piezoresistive pressure sensors for harsh environment applications

National Natural Science Foundation of China [51075344, 61274120, 51175444]; Fujian Province Major Projects on University-Industry Cooperation in Science and Technology [2013H6023]; Science and Technology Program of Xiamen [3502Z20123008, 3502Z20126006]

Silicon-Based Micro-Machined Infrared Emitters With a Micro-Bridge and a Self-Heating Membrane Structure

A micro-bridge membrane type (MBMT) infrared (IR) emitter is designed and fabricated to realize high IR radiation, low power consumption, and low thermo-mechanical stress. The suspended micro-bridge membrane, consisting of a heating layer and a self-heating support layer, is constructed in a silicon (Si) frame. A boron-doped poly-Si serves as the resistive heating layer to realize the IR radiation, and a heavily-boron-doped Si serves as the self-heating layer to absorb the backward IR radiation for storing the thermal energy and support the heating layer. The fabricated MBMT is thoroughly characterized by the electrical and optical measurements. The results reveal that MBMT emitters have higher photoelectric and mechanical performances than the closed membrane type emitters.

Study on dielectric charging in low-stress silicon nitride with the MIS structure for reliable MEMS applications

Charge-induced failure has been recognized as a primary reliability issue in capacitive micro-actuators. In this paper, we present a simple method to assess the effect of dielectric charging on reliability of a capacitive micro-actuator. By capacitance–voltage measurements for a metal–insulator–semiconductor (MIS) structure, the characteristics of dielectric charging can be investigated, and the obtained results can be used to study the charging behavior of a capacitive micro-actuator. An analytical model based on this method has been established. The silicon-rich nitride film was deposited by low-pressure chemical vapor deposition on silicon substrate. The current–voltage and capacitance–voltage measurements exhibit an asymmetric electrical characteristic under different polarity of stress voltage. The charging parameters of the silicon-rich nitride were extracted by the stretched exponential curve fitting method. This charging behavior suggests that silicon-rich nitride can be negatively or positively charged, and the injection and transport of holes are more favored than the injection and transport of electrons. The charge injection from movable electrode plays a dominant role in the dielectric charging of a capacitive micro-actuator. It is expected that the charge accumulation in dielectrics can be eliminated by employing the bipolar square-wave voltage to actuate a capacitive micro-actuator.

MEMS for vibration energy harvesting

In this paper, a capacitive vibration-to-electrical energy harvester was designed. An integrated process flow for fabricating the designed capacitive harvester is presented. For overcoming the disadvantage of depending on external power source in capacitive energy harvester, two parallel electrodes with different work functions are used as the two electrodes of the capacitor to generate a build-in voltage for initially charging the capacitor. The device is a sandwich structure of silicon layer in two glass layers with area of about 1 cm2. The silicon structure is fabricated by using silicon-on-insulator (SOI) wafer. The glass wafers are anodic bonded on to both sides of the SOI wafer to create a vacuum sealed package.

Electrochemically Reduced Graphene Oxide on Well-Aligned Titanium Dioxide Nanotube Arrays for Betavoltaic Enhancement

We report a novel betavoltaic device with significant conversion efficiency by using electrochemically reduced graphene oxide (ERGO) on TiO2 nanotube arrays (TNTAs) for enhancing the absorption of beta radiation as well as the transportation of carriers. ERGO on TNTAs (G-TNTAs) were prepared by electrochemical anodization and subsequently cyclic voltammetry techniques. A 10 mCi of (63)Ni/Ni source was assembled to G-TNTAs to form the sandwich-type betavoltaic devices (Ni/(63)Ni/G-TNTAs/Ti). By I-V measurements, the optimum betavoltaic device exhibits a significant effective energy conversion efficiency of 26.55% with an open-circuit voltage of 2.38 V and a short-circuit current of 14.69 nAcm(-2). The experimental results indicate that G-TNTAs are a high-potential nanocomposite for developing betavoltaic batteries.