We have reported that a low temperature growth (LTG) technique is effective to expand the lower growth temperature region of c-axis orientated SmBa2Cu3Oy (SmBCO) thin films so far. However, BaHfO3 (BHO)-doped SmBCO LTG-films show serious decrease of Jc at low magnetic field compared with conventional PLD-films. We investigated thickness dependence of SmBCO seed layers on LSAT single crystal. The result shows the seed layer is the cause of Jc decrease at low magnetic field due to flux line motion in the seed layer. In order to prevent the Jc decrease, we have tried to add Y2O3 in the seed layer on IBAD-MgO substrate. As a result, Sm-rich particles were formed in the seed layer, and those particles prevented flux line motion in the seed layer. After that, we measured the BHO-doped SmBCO films on Y2O3-doped seed layer at 77 K. As a result, the Y2O3-doped seed layer is effective at 77 K because the diameter of Sm-rich particle is about 17 nm which is larger than coherent length of 77 K in REBCO films. In summary, we improved Jc decrease at low magnetic field by adding the Y2O3 in the seed layer, and that film deposited by PLD-LTG technique showed high Jc at wide magnetic field.