A high rectification efficiency Si_(0.14)Ge_(0.72)Sn_(0.14)-Ge_(0.82)Sn_(0.18)-Ge quantum structure n-MOSFET for 2.45 GHz weak energy microwave wireless energy transmission

The design strategy and efficiency optimization of a Ge-based n-type metal-oxide-semiconductor field-effect transistor(n-MOSFET)with a Si_(0.14)Ge_(0.72)Sn_(0.14)-Ge_(0.82)Sn_(0.18)-Ge quantum structure used for 2.45 GHz weak energy microwave wireless energy transmission is reported.The quantum structure combined withδ-doping technology is used to reduce the scattering of the device and improve its electron mobility;at the same time,the generation of surface channels is suppressed by the Si_(0.14)Ge_(0.72)Sn_(0.14) cap layer.By adjusting the threshold voltage of the device to 91 mV,setting the device aspect ratio to 1μm/0.4μm and adopting a novel diode connection method,the rectification efficiency of the device is improved.With simulation by Silvaco TCAD software,good performance is displayed in the transfer and output characteristics.For a simple half-wave rectifier circuit with a load of 1 pf and 20 kΩ,the rectification efficiency of the device can reach 7.14%at an input power of-10 dBm,which is 4.2 times that of a Si MOSFET(with a threshold voltage of 80 mV)under the same conditions;this device shows a better rectification effect than a Si MOSFET in the range of-30 dBm to 6.9 dBm.

On the Mathematical Nature of Wireless Broadcast Trees

Trees are arguably one of the most important data structures widely used in information theory and computing science. Different numbers of intermediate nodes in wireless broadcast trees may exert great impacts on the energy consumption of individual nodes, which are typically equipped with a limited power supply in a wireless sensor network; this limitation may eventually determine how long the given wireless sensor network can last. Thus, obtaining a deep understanding of the mathematical nature of wireless broadcast trees is of great importance. In this paper, we give new proof of Cayley＇s well-known theorem for counting labeled trees. A distinct feature of this proof is that we purely use combinatorial structures instead of constructing a bijection between two kinds of labeled trees, which is in contrast to all existing proofs. Another contribution of this work is the presentation of a new theorem on trees based on the number of intermediate nodes in the tree. To the best of our knowledge,this work is the first to present a tree enumeration theorem based on the number of intermediate nodes in the tree.