| Atomic hydrogen cleaning (AHC) has been used to remove the native oxide layer from the surface of n-type (100) GaAs and GaSb wafers just prior to in-situ, ultra-high vacuum electron-beam metallization in order to fabricate ohmic contacts. Several metallization schemes were used in this work. High quality, low resistance, unalloyed and alloyed, ohmic contacts were demonstrated on n-type GaSb (7 x 1017 cm-3) and unalloyed, low resistance ohmic contacts using AHC were demonstrated on n-type GaAs (1 x 1018 cm-3). The n-type GaSb Ge/Au/Ni/Au contacts had specific contact resistance, rc, values between 1 x 10-2O-cm2 and 3 x 10 -3-O-cm2 before alloying at 300°C. After alloying, the rc values were reduced to approximately 2-3 x 10 -6 O-cm2. The n-type GaSb Au/Sn/Pt/Au contacts yielded low rc values with an unalloyed lowest value of 5 x 10 -7 O-cm2 and a typical range of 1-5 x 10 -6 O-cm2. The n-type GaAs Ge/Ni/Au contacts yielded unalloyed ohmic contacts with values for rc in a range from 3 x 10-5 O-cm2 to 1 x 10-6 O-cm 2. The n-type GaSb results demonstrated for the first time, the usefulness of using the AHC/in situ metallization technique to make high quality contacts to this material. |
