Effect of phosphine on plasma-induced traps in n-InP

Electron traps in n-InP generated by exposure to Ar or phosphine (PH 3 ) plasma have been investigated using isothermal capacitance transient spectroscopy (ICTS). One electron trap ( E c -0.54 eV) is generated by Ar-plasma treatment at 250°C for 60 min. Annealing at 350°C for 3 min after Ar-plasma treatment induces another electron trap ( E c -0.32 eV) together with an increase of the ( E c -0.54 eV) trap density. In contrast to the case of Ar plasma, no traps are detected in InP treated with PH 3 plasma consisting of Ar(90%) and PH 3 (10%) at 250°C for 60 min. Moreover, addition of PH 3 to hydrogen (H 2 ) plasma is shown to be effective in suppressing generation of the traps. Generation of these traps does not occur due to annealing after PH 3 -plasma treatment, while simple annealing of as-etched InP introduces these traps. It is demonstrated that PH 3 -plasma treatment leads to diffusion of phosphorus atoms during the process and deposition of a thin phosphorus layer at the surface of InP.