Device performance of GaAs metal- semiconductor field effect transistors (MESFETs) on conventional semi-insulating GaAs substrates has been limited by backgate or sidegate effects which can lead to undesirable cross-talk between neighboring devices and thus impose limits on packing densities. Recent research has shown that incorporation of a low temperature buffer layer grown by molecular beam epitaxy (MBE) can result in many performance improvements, including elimination of backgating. Because of its very high processing cost, MBE is not commercially viable production method. We propose to form an effect buffer layer using ion implantation, demonstrated manufacturable process. One of the dominant characteristics of the MBE-grown buffer layers is an excess of As in the film. Ion implantation is well suited to simulate the MBE layers since implantation conditions can be tightly controlled to precisely engineer the As profile by adjusting implantation parameters such as dose, energy, and dose rate. Phase I work is to use ion implantation to produce As-rich isolating buffer layers in GaAs. The structural and electrical properties of the buffer layers will be studied and compared to those of MBE-grown layers.
