Application of AlGaAs/GaAs superlattice for negative-differential-resistance transistor

Abstract

ABSTRACTA novel functional resonant—tunneling bipolar transistor (RBT) has been fabricated and demonstrated. In the proposed device, electrons are injected from emitter to base by resonant—tunneling through the minibands in the i—AlGaAs/n—GaAs superlattice. The mainfeature of the proposed device is the significant double negative—differential—resistance (NDR).Two high peak—to--valley current ratios of 4: 1 and 2.6: 1 were obtained at 77K. In the transistoroperation, a common—emitter current gain of over 60 and a collector ofset voltage smaller than O.2V at 77K were obtained. As control base current increases sufficiently to cause the base—emitter junction drop beyond flat—band condition, two different transistor action regions with smaller current gains of 38 and 35 are found, respectively. Furthermore, the first peak current is nearly equal to the second peak current and much larger than the second valley current.therefore, it is attractive to exploit the device in multiple—valued logic circuits and frequencymultiplier.1. INTRODUCTIONPioneering work on resonant—tunneling through a heterostructure quantum well was firstdone by Tsu and Esaki' and Chang et al.2 However, the observed negative—differential—resistanceeffects were too small to be useful in device applications. Recently, the remarkable progress in