▎ 摘　　要

We study the effects of impurities on the electronic properties of graphene. The tight-binding Hamiltonian with impurities has been diagonalized by a series of canonical transformations to obtain energy dispersions. Impurity effects on energy is observed as a band gap opening in donor type impurities, whereas acceptor type impurities do not create a gap. However the linear dispersions near the Dirac point turn to quadratic form for both types of impurities. Density of states are also calculated analytically.