The thermal diffusion of Pt atoms into n-type GaAs and GaN was studied (figure 3). It was noted that, although the diffusion of Pt into Si as a carrier lifetime reducer and leakage current minimiser had been examined, Pt diffusion into III-V semiconductors remained unexamined. Here, Pt was surface-coated and thermally diffused into (driven-in) GaAs and GaN samples at 500 to 900C. The corresponding diffusion constants and diffusion energies were then determined. Various luminescence spectra were observed and analyzed. Among the diffused samples, Pt was found to be a shallow donor in GaN, but was instead found as a deep acceptor in Pt-diffused GaAs samples.

Comparative Analysis of Platinum Diffusion Parameters in GaAs and GaN Semiconductors. L.Z.Hsieh, D.H.Yeh: Journal of Applied Physics, 2007, 102[2], 024507

Figure 3

Diffusivity of Pt in GaAs and GaN

(Upper line: GaAs, lower lines: GaN)