We report In0.53GaAs-channel gate-all-around FETs with channel width down to 7nm and Lg down to 36nm, the smallest dimensions reported to date for IIIV devices fabricated on 300mm Si wafer. Furthermore, we systematically study the device scalability. InGaAs S/D improves the peak gm by 25% compared to InAs S/D. A gm of 1310 µS/µm with an SSsat of 82mV/dec is achieved for an Lg=46nm device. At this Lg, a record Ion above 200µA/µm is obtained at Ioff of 100nA/µm and Vds=0.5V on a 300mm Si platform.