Charge-collection efficiency of GaAs field effect transistors fabricated with a low-temperature grown buffer layer: dependence on charge deposition profile

The dependence of the charge-collection processes of LT GaAs field-effect transistors on the depth profile of the deposited carriers is examined using computer simulation and laser-induced charge-collection measurements. The charge-collection simulations reveal a surprising dependence of the charge-collection efficiency on the location of the deposited charge, such that the charge-collection efficiency is largest for charge deposition below the LT GaAs buffer layer. These results implicate the significant role of charge-enhancement phenomena in the charge-collection processes of LT GaAs FETs. Experimental measurements performed as a function of the optical penetration depth support the conclusions of the simulation study.