Abstract
Er-doped InGaAsP epitaxial layers lattice-matched to InP with band gaps of 0.96 and 0.80 eV have been grown by liquid-phase epitaxy. All the Er-doped samples still exhibit n-type conduction, even though relatively large amounts of Er of up to -0.35 wt% were added to the growth solutions. The carrier concentrations of Er-doped InGaAsP layers are around 3 — 30 x 10 14 cm -3 and are one to two orders of magnitude lower than those of undoped layers. By 300- and 16-K photoluminescence measurements, we can observe that the full width at half-maximum of photoluminescent peaks related to the near band-to-band transition has been effectively reduced. The low carrier concentrations and narrow linewidths are better than those previously reported for layers of the same composition. We thus conclude that the dominant process occurring during the growth of InGaAsP layers in the presence of Er elements is a very efficient gettering of residual donors. © 1991, IOP Publishing Ltd.