IMPROVEMENTS TO THE SCHOTTKY-BARRIER HEIGHTS OF INTIMATE METAL-INGAASCONTACTS BY LOW-TEMPERATURE METALLIZATION

One challenge in the processing of In53Ga47As/InP(100) heterostructure s is the enhancement of the low Schottky barrier heights (phi(b)) typi cally exhibited by metal-nIn(53)Ga(47)As(100) contacts. Previous studi es of the metallisation of chemically etched In53Ga47As surfaces have reported increases in phi(b) if metallisation is performed at 77 K. Th is study extends this concept to probe the idealised case of the forma tion of metal contacts (Au-, Cu- and In-) to atomically clean nIn(53)G a(47)As/InP(100) at 80 K and room temperature (294 K). The in-situ cur rent-voltage measurements of intimate Au and Cu contacts formed at bot h temperatures exhibited ohmic characteristics. However, intimate In c ontacts formed at 80 and 294 K showed diodic behaviour (phi(b) approxi mate to 0.45 and 0.30 eV, respectively), with an improvement in the re ctification when formed at 80 K. Conversely, In contacts to etched sur faces were ohmic, It is proposed that this behaviour is linked to the alteration of the structure and nature of the interface as a result of the various fabrication techniques. These results indicate the potent ial to select phi(b) on In53Ga47As via a combination of cryogenic proc essing and surface preparation.