Picosecond charge-collection dynamics in GaAs MESFETs [for space application]

Ion and picosecond laser induced charge-collection measurements performed as a function of temperature and device bias conditions reveal the significant changes that occur in the charge collection transients as a function of these parameters. The temperature-dependent results provide new evidence that above-bandgap picosecond laser excitation can reproduce the primary features of the ion induced charge-collection transients measured for GaAs MESFETs. Bias dependence results reveal clearly the sensitive role of the device operating point in determining both the shape and the total integrated intensity of the measured charge-collection transients. Preliminary two-dimensional computer simulation results are presented which suggest carrier-induced channel modulation as the primary mechanism for enhanced charge collection in GaAs MESFETs