The impact of strain engineering on hole mobility of In(x)Ga(1-x)As channels for III-V pMOSFET

Whilst the high electron mobility of compound semiconductors makes them attractive for beyond 22 nm CMOS, a key challenge in implementing III-V materials is their modest hole mobility. Addressing this issue motivates an investigation of the impact of strain to optimize the hole transport properties of III-V MOSFET channel materials. In this work, the researchers describe the dependence of hole mobility on the bi-axial compressive strain of InxGa1-xAs layers with indium concentrations in the range 53%-85%. The vertical architecture of the material structure of this study resembles a III-V high mobility transistor where the dopant is spatially separated from the device channel. Mobility and channel carrier concentration were determined using Hall effect measurements. While the 53% In-content (0% strain) structures demonstrated modest mobilities of 60-70 cm2/Vs, the strained structures exhibited superior transport with the 85% In-content (2.1% strain) channel demonstrating mobilities of 427-433 cm2/Vs with sheet hole densities of 1.33e12 - 1.6e12 cm-2 depending on the doping level used. To their knowledge, the room temperature mobility of the 2.1% strained structures are the highest ever reported for an InxGa1-xAs channel