Analyses On Mechanical Characteristics Of Single-barrier Quantum Well Capacity Varactor

In recent years, with the development and application of MBE(Molecular BeamEpitaxy) and NEMS(Nano-Electromechanical System) fabrication technology, various superlattice quantum-well devices have been fabricated. When the critical dimension of the device approaches nanometer magnitude, several effects including the quantum effect will appear. Because of the dimensional effect, these novel devices will show new characteristics and good performances. In this paper, we introduced a new sensor which is based on Meso-piezoresistance Effect. The sensor is single potential barrier quantum-well capacity varactor. The band, parameters and physical properties will be changed changing the structural stress of the single potential barrier quantum-well. Finally, the sensitivity and capacitance modulation ratio of the capacitive varactor can be improved. High capacitance modulation ratio means high frequency of devices and high capacitance modulation ration means high frequency of devices.In this paper we discuss the transmission process of the electron wave from the emitter transferring to the collector in detail. The material of the single potential barrier quantum-well structure between the emitter and collector is InGaAs/AlAs/InAlAs. We deduced the reflection coefficient, transmission coefficient and the current transmission formula. We also introduced the method of decreasing the conduction current. On the base of Meso-piezoresistance Effect, we simulated the capacitance changes of capacity varactor by using Matlab software. Finally, the modulation ratio of capacity actor is increased.The main research contents below:(1) The material of superlattice quantum-well is analyzed andâ…¢-â…¤elements are introduced. The appropriate barrier materials are selected and the barrier structure is listed.(2) We introduced transmission of electronic wave and the band structure of single potential barrier quantum-well capacity varactor diode.(3)The method of decreasing the conduction current of single potential barrier quantum-well capacity varactor is introduced.(4) By analyzing the single-barrier structure which is in large bias or small bias, we deduced the formula of capacitance in large-bias and small-bias. The change of the single-barrier structure on certain stress is introduced in detail. The Meso-capacity factor of capacity varator id deduced. Finally, the sensitivity of capacitive varactor and capacitance modulation ratio is improved.