Dc performance of ballistic tunneling hot-electron transfer amplifiers

Abstract

We present new experimental results of ballistic electron transport through thin n+-GaAs layers. Measurements were done on tunneling hot-electron transfer amplifier devices composed of GaAs and AlGaAs layers. In devices with GaAs active regions (bases) of 300 and 800 Å, collisionless or ballistic transport was observed. By performing hot-electron energy spectroscopy we found that the collected ballistic distributions were similar in shape but differed in magnitude. This suggests the existence of a strong scattering mechanism which randomizes the otherwise ballistic electrons. The maximum differential current transfer ratio α was 0.9 in devices for which about 75% of the injected current traversed the base ballistically. The presence of ballistic transport has also allowed the measurement of the AlGaAs barrier height through observation of the onset of current collection in the devices. Barrier heights higher than those recently reported have been measured. In addition we show the effects of grading the collector barrier. The most noted effect in these cases was a higher transfer ratio.