Effect of Strain in Channel on Electron Transport Properties of Ga_1−xIn_xSb High Electron Mobility Transistor Structures with Strained‐Al_0.40In_0.60Sb/Al_0.25In_0.75Sb Stepped Buffer

GaInSb is one of the attractive Sb‐based channel materials for high electron mobility transistors (HEMTs) that can operate in the terahertz band. The effect of strain in the channel on the electron transport properties of Ga 1− x In x Sb channel HEMT structures ( x = 0.60, 0.78, 0.85, 0.90, and 0.94) with the strained‐Al 0.40 In 0.60 Sb/Al 0.25 In 0.75 Sb stepped buffer is investigated. The strain in the Ga 1− x In x Sb channel layer is determined by the lattice constant of Al 0.25 In 0.75 Sb lower buffer layer. The electron mobility ( μ ) shows the maximum value of 15 100 cm 2 V −1 s −1 at x = 0.78 (unstrained), which has the minimum threading dislocation density (TDD). The value for sheet electron density ( N s ) increases with decreasing x , and saturates at about 2.1 × 10 12 cm −2 when unstrained or tensile strained. The minimum sheet resistance ( R s ) is 202 Ω/□ for the unstrained Ga 0.22 In 0.78 Sb channel.