Schottky enhancement of contacts to n-(In0.52Al0.48)As using PdAl as a metallization

Abstract

PdAl was selected as a reactive contact to n-(In 0.52 Al 0.48 )As with the intention of forming a thin, AlAs-enriched interlayer of graded (In 1-x Al x )As semiconductor alloy, following rapid thermal annealing. Selection of PdAl was based on the experimentally established existence of a quasi-reciprocal phase relationship. A Schottky barrier enhancement of 0.07 eV (measured by current-voltage (I-V)) and 0.09 eV (measured by capacitance-voltage (C-V)) was found following a 1-min anneal at 450°C. High-resolution transmission electron microscopy (HRTEM) examination showed the presence of an edge dislocation in the interlayer alloy, suggesting an enrichment of AlAs. Schottky barrier enhancement is in qualitative agreement with the prediction of the combined thermodynamic/kinetic model.