CURRENT-VOLTAGE CHARACTERISTICS OF GAAS ALAS DOUBLE-BARRIER RESONANT-TUNNELING DIODES WITH A SI-PLANAR-DOPED BARRIER/

Current-Voltage (I-V) characteristics of GaAs/AlAs double-barrier reso nant tunneling diodes (RTDs) with a Si-planar-doped barrier are studie d. At 4.2 K the peak-to-valley current ratio decreased when Si was int roduced to the barrier next to the electrode from which electrons are emitted (emitter barrier). On the other hand, the ratio did not decrea se considerably when Si was introduced to the other barrier, i.e., nex t to the electrode into which electrons flow (collector barrier). To i nvestigate the origin of the decrease in the peak-to-valley ratio, we evaluated the transmission coefficient experimentally, and found that the resonance transmission widths for the double-barrier RTDs are almo st the same. This means that the reduction in the peak-to-valley curre nt ratio is not caused by the broadening of resonance transmission wid th. To explain why the peak-to-valley current ratio is degraded, we th en introduced a new model in which an excess current flows through don or levels in the emitter barrier. To confirm this model, we investigat ed the I-V characteristics of GaAs/AlAs single-barrier diodes. We foun d an excess current, which is probably due to a tunneling current thro ugh the donor level created in the barrier, when the barrier is planar -doped. It is, therefore, concluded that the decrease in the peak-to-v alley current ratio observed for the RTD with the doped emitter barrie r is due to this excess current flowing through the doped emitter barr ier. (C) 1996 American Institute of Physics.