EFFECTS OF PHOSPHORUS PRESSURE ON LOW-ENERGY EMISSION BANDS IN ZN-DIFFUSED INP

The effects of phosphorus pressure during Zn diffusion and sequential annealing on the diffusion profiles and the photoluminescence spectra were investigated by secondary ion mass spectrometry (SIMS) analysis, capacitance-voltage (C-V) and photoluminescence (PL) measurements. Zn diffusion was performed using dimethylzinc as the Zn source. We found that as the PH3 flow rate increased, the diffusion depth deepened and a low-energy broad emission band at 1.23-1.32 eV (77 K) from near the Zn-diffused surface shifted to higher energy while its intensity increased. Another low-energy emission band at 1.28-1.33 eV (77 K) was observed in the Zn-diffused InP with high Zn interstitial concentration. The excitation and temperature dependences of the peak energies indicate that these bands are the so-called quasi-donor-acceptor pair bands with lattice relaxation. These results, along with the effect of annealing, suggest that a Zn incorporation mechanism with a contribution from phosphorus-related defects occurs near the surface.