This study describes the dependence of the surface electric field to the junction depth of source/drain-extension, and the suppression of gate induced drain leakage (GIDL) in fully depleted shallow junction gate-overlapped source/drain-extension (SDE). The GIDL can be reduced by reducing shallow junction depth of drain-extension. Total space charges are a function of junction depth in fully depleted shallow junction drain-extension, and the surface potential is proportional to these charges. Because the GIDL is proportional to surface potential, GIDL is the function of junction depth in fully depleted shallow junction drain-extension. Therefore, the GIDL is suppressed in a fully depleted shallow junction drain-extension by reducing surface potential. Negative substrate bias and halo doping could suppress the GIDL, too. The GIDL characteristic under negative substrate bias is contrary to other GIDL models.