Abstract
Current-voltage characteristics of single and three period modulation doped heterostructures intended for high speed FETs are compared. Single period structures exhibited linear characteristics up to 2 kV/cm at 300 K and non-linear characteristics were observed at lower temperatures. Three period structures grown under similar conditions showed negative differential resistance at field strengths above 1 kV/cm, which is attributed to structural properties of interfaces between the ternary and the overlaying binary layers. Although it is possible to improve these interfaces associated with multiple period structures somewhat, the single period structures were found more suitable for high speed FET applications.