Effect of Strain on Electron Transport and Quantum Lifetimes in InxGa1−xAs/In0.52Al0.48As Modulation Doped Double Quantum Well‐Based High Electron Mobility Transistor Structures

The effect of tensile and compressive strain on low‐temperature electron transport ( τ t ) and quantum ( τ q ) lifetimes are analyzed as function of well width ( w ) in In x Ga 1− x As/In 0.52 Al 0.48 As 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 τ t and τ q relates to the uneven dependence on the ionized impurity ( ii ), interface roughness ( ir ), and alloy disorder ( al ) scatterings. As w increases, τ t enhances. The improvement in τ t 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 τ t ( x = 0.41) > τ t ( x = 0.75). Conversely, τ q is dominated by ii ‐scattering exhibiting τ q ( x = 0.75) > τ q ( x = 0.53) > τ q ( 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 τ t for w = 150 Å compared to the symmetric structures.