High mobility multilayered heterojunction devices employing modulated doping

摘要

{PG,1 The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10{hu 14{l /cm{hu 3{l , whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10{hu 16 {l to 10{hu 18{l /cm{hu 3{l . The incorporation of this structure in an FET is also described.