Fabrication And Reseach Of Four Sorts Of Novel Three-terminal NDR Devices Compatible With HBT Process

In this thesis, four kinds of novel three-terminal negative differential resistance(NDR) devices, including ultra-thin base NDR HBT based on InGaP/GaAs andAlGaAs/GaAs material system, double base NDR HBT, resistive gate NDR HBT andS-shape bi-directional NDR transistor, were studied. Material structure design andpreparetion, device structure and photomasks design, chip process, performancetesting and analyse, device simulation, and physical mechanism analyse wereinvolved in the systemic work. For these four kinds of devices were reported little inthe world, many aspects are creative and many experiment phenomena are observedfor the first time.Followings are the main achievements of the thesis:1. 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. The maximal peak-to-valleycurrent rate (PVCR) is not lower than 4400. In addition, variationalvoltage-controlled NDR with VC increasing was detected.2. 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 and the maximalPVCR is not lower than 1100.3. Through testing results analyse and device simulation, the physical mechanism ofultra-thin base NDR HBT was explained as bipolar-to-bulk barrier transformmechanism. Experiment phenomena including current-controlled NDR, NDRdisperse and peak current rise with VC increasing, were analysed.4. Combining the conception of Si planar double base transistor with the structureand process of HBT, double base NDR HBT were designed and fabricated. It hadseveral shapes of voltage-controlled NDR. At the same time, variability ofvoltage-controlled NDR with VC and ligh-controlled NDR were detected. Allphenomena were analyzed according to device simulation and experiment results.5. A resistive gate NDR HBT was tentatively fabricated. Its voltage-controlled NDRwas confirmed. The maximal PVCR tested was not lower than 215. The cause ofNDR was explained and the device's physical model was established.6. Compound heterojunction structure S-shape bi-directional NDR transistor wasdesigned and fabricated through introducing the work mechanism of Si planarbi-directional NDR transistor into the material structure of HBT. The experimentresult certificated the feasibility of this thought.