PdIn contacts to n-type and p-type GaP

Abstract

PdIn was used as a contact material to n-type and p-type GaP. On n-type GaP it forms a low resistance ohmic contact upon rapid thermal annealing. PdIn/n-GaP (S doped at 2–3 ×1018 cm−3) contacts annealed at 600 °C for 1 min had specific contact resistance’s lower than 1×10−4 Ω cm2. Unlike the contacts to n-GaP, PdIn contacts to p-GaP (Zn doped 1–2×1018 cm−3) show rectifying behavior at all annealing conditions. However, the effective Schottky barrier height seems to decrease significantly with thermal annealing. In addition to the electrical measurements, glancing angle x-ray diffraction was used to characterize the contacts. The glancing angle x-ray diffusion pattern of PdIn/n-GaP, annealed at 600 °C for 1 min, is consistent with the formation of an (InyGa1−y)P phase due to the thermal annealing. The ohmic behavior of the PdIn contacts to n-type GaP and the decrease in the contact’s Schottky barrier height on p-type GaP is attributed to the formation of this (InyGa1−y)P phase at the contact’s interface.