Simulation And Experimental Study Of NDRHBT

The paper is based on the scientific research project, which is named "Researchon Negative Resistance Heterojunction Bipolar Transistor", and focused on thesimulation and experimental study of ultra-thin base NDR HBT based onInGaP/GaAs and AlGaAs/GaAs material system and double base NDR HBT.Firstly, the negative resistance characteristics of these two devices with differentstructures have been analysed in theory. With the aid of device simulation softwareATLAS from SILVACO Inc., the two devices were investigated. According to the I/Vcharacteristic curves obtained by device simulation, we explained the mechanisminducing the negative resistance characteristics. At the same time, material structuredesign and preparetion, device structure and photomasks design and chip processwere carried on. Result of device simulation and performance testing were taken inconsideration together for further analyse of the negative resistance mechanism.Following are the main products of this paper:1. Through the comparison and analysis of device simulation and testing results, thephysical mechanism of ultra-thin base NDR HBT was explained asbipolar-to-bulk barrier transform mechanism. Experiment phenomena includingvoltage-controlled and current-controlled NDR and the factors which affect NDRcharacteristics were analysed.2. Ultra-thin base NDR HBT with 8nm thickness base based on InGaP/GaAsmaterial system was successfully designed and fabricated using selective wetchemical etch. For the first time both voltage-controlled NDR andcurrent-controlled NDR were observed in one device..3. Ultra-thin base NDR HBT with 8nm thickness base based on InGaP/GaAsmaterial system was successfully designed and fabricated using selective wetchemical etch. Distinct voltage-controlled NDR were observed.4. Combining the conception of Si planar double base transistor with the structureand process of HBT, double base NDR HBT were simulated by ATLAS. It wasalso been designed and fabricated, and was found with several shapes ofvoltage-controlled NDR. The influential factors on NDR characteristics wereanalyzed according to device simulation and experiment results.