In this paper, we have studied the effect of systematic downscaling of MOS channel length of the performance of the hybrid GaN MOS-HEMT with numerical simulations. The improvement in on-state conduction, together with concomitant short channel effects, including drain induced barrier lowering (DIBL) is quantitatively evaluated. A specific on-resistance of 2.1 m Omega cm(2) has been projected for a MOS channel length of 0.38 mu m. We also have assessed the impact of high-k gate dielectrics, such as Al2O3. In addition, we have found that adding a thin GaN cap layer on top of AlGaN barrier can help reducing short channel effects. (C) 2010 Elsevier Ltd. All rights reserved.