Effect of Strain on Electron Transport and Quantum Lifetimes in In_xGa_1−xAs/In_0.52Al_0.48As Modulation Doped Double Quantum Well‐Based High Electron Mobility Transistor Structures

Abstract

The effect of tensile and compressive strain on low‐temperature electron transport (τt) and quantum (τq) lifetimes are analyzed as function of well width (w) in InxGa1−xAs/In0.52Al0.48As modulation‐doped double quantum well (MD‐DQW)‐based high electron mobility transistors structures. The DQW system can be made either lattice‐matched or strained, tensile and compressive, by considering x = 0.53, 0.41, and 0.75, respectively. Results show that the nonlinearity in τt and τq relates to the uneven dependence on the ionized impurity (ii), interface roughness (ir), and alloy disorder (al) scatterings. As w increases, τt enhances. The improvement in τt is substantial for the strained system compared to the unstrained. Further, for w < 94 Å, the ir‐scattering is more dominating under the compressive than the tensile strained structure, leading to τt (x = 0.41) > τt (x = 0.75). Conversely, τq is dominated by ii‐scattering exhibiting τq (x = 0.75) > τq (x = 0.53) > τq (x = 0.41). A hybrid structure is also proposed with one well tensile (x = 0.41) and the other as compressively (x = 0.75) strained, resulting in a step‐like MD‐DQW structure. As a result, only a single sub‐band is occupied leading to a twofold improvement in τt for w = 150 Å compared to the symmetric structures.