Conventional techniques to characterize the carrier transport properties in high-electron-mobility transistors do not account for the effect of each individual unit process and device integration, and can be challenging to use for short-channel devices. To overcome this, we have developed a new technique that consists of measurement and analysis of the transconductance scaling behavior. The proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{m}$ </tex-math></inline-formula> modeling technique yielded the effective mobility, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{n\_{}{\textit {eff}}}$ </tex-math></inline-formula> , and saturation velocity, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${v}_{\textit {sat}}$ </tex-math></inline-formula> for fabricated InxGa <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{1}-{x}}$ </tex-math></inline-formula> As Quantum-Well (QW) HEMTs, correlating the carrier transport properties to the device characteristics. This helps illuminate the physics of the carrier transport properties of HEMTs from the mobility relevant to the velocity saturation regimes.