Origin of High Mobility in InSnZnO MOSFETs

The origins of higher mobility characteristics of In-Sn-Zn-O (InSnZnO) MOSFETs than those of conventional In-Ga-Zn-O (InGaZnO) MOSFETs were investigated. Comprehensive analyses of temperature and surface carrier concentration (
${N} _{s}$
) dependence of mobility revealed the aspects of potential profile around mobility edge (
${E} _{c}$
) in InSnZnO MOSFET. Incorporated Sn atoms were found to increase the potential fluctuation around
${E} _{c}$
at low
${N} _{s}$
compared to conventional InGaZnO MOSFET, but enhance the overlapping of electron orbitals of cations with In atoms, which results in mobility improvement by band transport.