| Research Abstract |
Scanning hot electron microscopy(SHEM) for the observation of the electron wave diffraction has been studied. Before this study, hot electrons of relatively high energy (3 to 4eV) from insulator/metal emitters were already detected. Our final target is to observe the hot electron of low energy(30 to 300meV) from the semiconductor emitter. Thus, the establishment of SHEM technique, the realization of the semiconductor emitter, and the detection of the hot electron of relative high energy(3eV) in semiconductor, were set as targets of this study. The reason for the choice of 3eV rather than 300meV is to avoid the necessity of the low work function metal on the sample surface. As results, (1)The comprehensive understanding of SHEM was achieved. Using the sphere/plane model, the jelium-model- and the image- force-potentials, the hot and the thermal-equilibrium electron currents flown through the probe, and their ratio were revealed in relation with parameters. (2)Parasitic effects including
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of the capacitive coupling current, the residual series resistance induced current, the phase-shift and response suppression induced by the gap control system, have been made clear to be eliminated. (3)AlAs/GaInAs hot electron emitters were designed and fabricated. The hot electron emission at 3eV was achieved. (4)Using the emitter and eliminating of parasitic effects, detection experiments of the hot electron from the semiconductor emitter have been executed. Measured data have been investigated comprehensively by comparing with the theory not to indicate the hot electron detection. We concluded that the 3eV hot electron could not be transported over 100nm in the semiconductor at the efficiency enough high for the probe detection. Summarizing the above, we have established SHEM technique and the hot electron generation by the semiconductor emitter. Based on these, we have convinced that we should proceed to the final stage where the object is the low energy hot electron. A breakthrough idea for imaging has been got to avoid the use of the low work function metal. Less
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