  We study the effect of disorder and doping on the metal-insulator transition
in a repulsive Hubbard model on a square lattice using the determinant quantum
Monte Carlo method. First, with the aim of making our results reliable, we
compute the sign problem with various parameters such as temperature, disorder,
on-site interactions, and lattice size. We show that in the presence of
randomness in the hopping elements, the metal-insulator transition occurs and
the critical disorder strength differs at different fillings. We also
demonstrate that doping is a driving force behind the metal-insulator
transition.
