CAPACITANCE OF RESONANT-TUNNELING DIODES WITH SPACER LAYERS

Self-consistent calculations have been performed on a double barrier r esonant tunneling diode (RTD) with asymmetric spacer layers under vari ous biases. The quasi-static state charge distribution in the GaAs-Al0 .3Ga0.7As RTD was studied and the capacitance derived. The theoretical capacitance-voltage (C-V) characteristic agrees qualitatively with ex perimental results. In contrast to the general belief that charge accu mulation in the quantum well results in the observed peak in capacitan ce measurements, our results reveal that the peak is induced by the qu antum well discharging process. Comparison between the theoretical and experimental results also supports the suggestion that scattering and localization effects are important in the device. Conditions for opti mizing the C-V characteristic for high frequency operations are discus sed.