Comparative Study of Heterosturcture Barrier Diodes in the GaAs/AlGaAs System

A comparative study of the electron transport property and operation of the Potential Well Barrier (PWB) diode and Planar-doped Potential-well Barrier (PPB) diode has been carried out in this study. Both diodes are heterostructures in GaAs/AlGaAs system with similarities in layer design though, with a sheet charge inserted close to the well of the PPB diode. A drift-diffusion and Monte Carlo simulation models were used throughout the study to examine the behavior of electrons in terms of the electric field distribution across the diodes, electron velocities, electron energy and densities. Results of simulation has shown how the electric field varies in the left and right intrinsic regions of the device and the effect of the field on velocity. The I-V characteristics of the experimental and simulation results have shown a good agreement in the two diodes though, with little adjustment of about ± 2.5% to design parameters in order to obtain a good fit with experimental results. The I-V characteristics of the diodes reveal that the PPB diode turns on at a higher voltage than the PWB diode though, with a better asymmetry in the reverse bias operation. This is because the sheet charge in the PPB diode produces additional charge and together with the charge in the well, presents a higher potential barrier than the PWB diode whose barrier is determined by the charge in the well only. The diodes demonstrate promising RF behavior with voltage responsivity of 10900V/W and 6400V/W at 10GH for the PPB and PWB diodes respectively.