Hole mobility and remote scattering in strained InGaSb quantum well MOSFET channels with Al2O3 oxide

Group III–V compound semiconduc-tors due to their better transport properties (mobility, effec-tive mass, injection velocity) have significant advantages over Si-based metal–oxide–semiconductor field effect transistors (MOSFETs) for high-speed and low-power digital applications. Substantial progress has been made in n-type InGaAs MOSFETs over the last 5–7 years [1–3] which also requires parallel development of p-type MOS-FETs for future high performance CMOS applications. The group III–Sb semiconductors have the highest bulk hole mobility among compound semiconductors, and in a strained two-dimensional channel a lower “in-plane” effec-tive mass corresponding to the heavy hole subband, as compared to their major p-type competing material, Ge [4]. The potential superior transport in inversion layers of 2% strained InGaSb semiconductors was projected by Monte-Carlo simulations [5] and more recently demonstrated in long-channel p-MOSFETs by a few groups [6, 7]. Superior transport properties are a major reason why III–V’s are considered for advanced CMOS circuits. How-ever, placing the semiconductor channel in close proximity to the high-k gate oxide reduces mobility significantly in a way similar to the Si or n-type InGaAs channels due to in-terface roughness, soft phonon, and remote Coulomb scat-tering (RCS) [8–11]. Understanding of the transport degra-dation mechanisms due to interface and oxide scattering is an important issue, and the corresponding baseline data will constitute a basis for comparison of prospective p-type materials for novel CMOS circuits.