Double-doped double-strained modulation-doped field effect transistor: 3D-SMODFET.

摘要

This dissertation reviews the operation of MODFETs and the current status they have achieved as the world's fastest transistor. The utilization of AlGaAs/InGaAs heterostructures in the MODFET has resulted in the wide spread use of PHEMTs in the microwave industry today. This structure's increasing popularity is mainly due to the improvement in the quality and price of GaAs substrates over the past ten years. As the cost of good semi-insulating GaAs substrates has dropped, economic forces and the industries' need for microwave applications (wireless market) have driven the PHEMT into the production line of many companies world wide. The cost advantages of monolithic integration has results in the wide spread applications of monolithic microwave integrated circuits (MMIC). The advantages of the AlInAs/InGaAs heterostructure are numerous and will be discussed in detail within this dissertation. The simple fact of this is the continued research in using the AlInAs/InGaAs heterostructure on GaAs substrates with the inherent problems of the large lattice mismatch.;Results of this careful optimization of the AlInAs/InGaAs MODFET on InP substrates are an exceptional industry record high 2DEG sheet charge of ;In this dissertation the careful optimization of the AlInAs/InGaAs heterostructure for use in MODFET structures is done. In reviewing epitaxial designs for AlInAs/InGaAs heterostructures it became clear that the common InP-based MODFET was not optimized. This conclusion is based on the fact when comparing the AlInAs/InGaAs MODFET to the AlGaAs/InGaAs PHEMT they received a lot of bang for the buck. The large conduction band discontinuity (