Highly doped In0.52Al0.48As growth and ohmic contact formation

The properties of ohmic contacts to metallorganic, chemical vapour deposited In0.52Al0.48As layers are described. The Pt/Ti bilayer metallization scheme was applied to a p-type InAlAs layer (Zn-doped approximately 5*1018 cm-3) in an attempt to produce an ohmic contact. The as-deposited system exhibited rectifying behaviour with a barrier height of about 0.40 eV. Rapid thermal processing even at temperatures of 300 degrees C led to the formation of an ohmic contact. The lowest specific resistance value of 2.5*10-5 Omega cm-2 was measured for the Pt/Ti/InAlAs contact after heating at 450 degrees C for a period of 30 s. The contact microstructure was stable through heating cycles at temperatures up to 500 degrees C, above which extensive interfacial reactions were observed.