Experimental correlation between substrate properties and GaAs MESFET transconductance

The relationship between the characteristics of FET´s obtained by direct ion implantation and the properties of a GaAs semi-insulating substrate was investigated. A positive correlation was observed between the dislocation etch-pit density, the as-grown mobility, the mobility after implantation, and the device transconductance. The observation of dislocations´ effect on mobility is consistent with the model that dislocations act as segregation centers for imperfections. Localized substrate inhomogeneties are shown to affect the GaAs FET´s frequency performance via the mobility.