Effect of Strain in Channel on Electron Transport Properties of Ga1−xInxSb High Electron Mobility Transistor Structures with Strained‐Al0.40In0.60Sb/Al0.25In0.75Sb Stepped Buffer

Abstract

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 Ga1−x In x Sb channel HEMT structures (x = 0.60, 0.78, 0.85, 0.90, and 0.94) with the strained‐Al0.40In0.60Sb/Al0.25In0.75Sb stepped buffer is investigated. The strain in the Ga1−x In x Sb channel layer is determined by the lattice constant of Al0.25In0.75Sb lower buffer layer. The electron mobility (μ) shows the maximum value of 15 100 cm2 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 × 1012 cm−2 when unstrained or tensile strained. The minimum sheet resistance (R s) is 202 Ω/□ for the unstrained Ga0.22In0.78Sb channel.