Improved Electron Transport Properties in InSb/Ga _0.22 In _0.78 Sb Composite Channel HEMT Structures

GaInSb is a promising Sb‐based channel material for high electron mobility transistors (HEMTs) targeting ultra‐high frequency operation. In this study, we fabricate double‐sided Te δ‐doping InSb/Ga 0.22 In 0.78 Sb composite channel HEMT structures employing GaSb buffer and AlInSb graded buffer structure. Te δ‐doping time on the lower side is optimized so as not to induce electron buffer leakage, resulting in a 25% increase in sheet electron density ( N s ). The effects of GaSb buffer and AlInSb‐graded buffer on threading dislocation (TD) behavior are quantitatively evaluated using a dislocation pair‐annihilation model, which provides a unified framework for assessing the impact of buffer design on TD reduction. As a result, TD density is reduced by 79%, yielding a 38% enhancement in electron mobility ( μ ) compared to a conventional buffer structure. Eventually, the optimized HEMT structure achieves μ = 19,800 cm 2 V −1 s −1 , N s = 3.35 × 10 12 cm −2 , and a low sheet resistance ( R s ) of 94.3 Ω/□, demonstrating its promise for terahertz‐range transistor applications.