Measurement of the Extrinsic Room-Temperature Minority Carrier Lifetime in GaP

Abstract

The room-temperature time decay of the near band-gap luminescence in GaP for time decays longer than about 5 nsec is shown to measure the minority carrier lifetime. Rise-time measurements with mode-locked argon laser pulses confirm this interpretation. Minority carrier lifetimes in n- and p-type GaP LPE dipped material at room temperatures have been measured and range up to 450 nsec. The minority carrier lifetime in Zn- and Te-doped GaP is determined by unintentionally present recombination centers. Annealing in GaP green material is found to produce random changes in the minority carrier lifetime. This method of using the green luminescence decay time for measuring the room-temperature minority carrier lifetime has also been applied to Zn, O-doped GaP. In this case, the measurement can be aided by the introduction of trace nitrogen. Spectral line-shape measurements which closely approximate the internal emission spectra have shown that phonon-assisted free-exciton recombination is the primary source of the green emission in non-nitrogen-doped (N < 1017 cm−3) GaP at room temperature. Bound-exciton recombination dominates in nitrogen-doped material (N ∼ 1018−1019 cm−3).