Antimonide based compound semiconductors have gained considerable interest in recent years due to their superior electron and hole transport properties . A Mixed anion InAsySb1-y quantum well heterostructure with high electron mobility of 13,300 cm2/Vs has already been demonstrated at a sheet carrier density of 2×1012 /cm 2, albeit for a thick EOT quantum well (QW) structure . A thin EOT structure is desired for improving short channel effects while maintaining the high electron mobility in the QW. In this paper, we study the low field electron transport properties in the high mobility InAs0.8Sb0.2 quantum well as we scale the QW heterostructure. Fig. 1(a),(b) show the schematic of the thick (TQW=12nm) and scaled (TQW=7.5nm) quantum well FET structure using InAs0.8Sb0.2 as channel material, In0.2Al0.8Sb barrier layer and an ultra-thin GaSb surface layer for avoiding surface oxidation of Al in the barrier . Fig. 2(a),(b) show the simulated energy band diagram of the two structures using self-consistent Schrodinger-Poisson simulation, indicating strong electron confinement in the QW. The effect of nonparabolicity on thick QW with T QW=12nm has already been studied and an effective mass (m*) of 0.043m0 has been extracted experimentally . For scaled QW the subband spacing was adjusted in order to achieve electron sheet charge density as a function of temperature, and the extracted density of states m*=0.05m0 was correlated to the transport effective mass. Experimental work to verify the obtained effective mass for scaled QW is underway.