Theoretical formalism to understand the role of strain in the tailoring of hole masses in p-type InxGa1−xAs (on GaAs substrates) and In0.53+xGa0.47−xAs (on InP substrates) modulation-doped field-effect transistors

Recently, experimental studies have suggested that strained p-channel modulation-doped field-effect transistors (MODFET’s) display enhanced characteristics due to a decrease in hole masses. In this letter, we examine the potential of using biaxial compressive strain to lower the effective mass of the hole gas. The Kohn–Luttinger Hamiltonian is used to describe the hole states in a strained channel. Using this, the Schrödinger equation is solved self-consistently with the Poisson equation. The coupling between light- and heavy-hole states is found to be critical to get accurate properties of the hole gas. A decrease in the effective hole mass of more than three times is found at low temperatures in the presence of the biaxial strain. The theoretical technique described here is not variational in nature and can be applied to an arbitrarily shaped confining potential profile with different material parameters across interfaces. This technique should be quite useful in designing and understanding strained p-MODFET devices.