AninsituOhmic‐contact‐formation technique forn‐ andp‐GaAs of any resistivity by molecular beam epitaxy was described. The measured specific contact resistances lie between low‐10−6&OHgr; cm2and mid‐10−5 &OHgr; cm2. The contacts were Ohmic for currents in excess of 250 mA tested in both forward and reverse directions. Furthermore, the contact metallization was optically smooth as no sintering or alloying process was needed. Excellent uniformity of electrical quality of the Ohmic contacts on the same sample was obtained.