Characterisation of Mn-doped and nominally pure LPE GaxIn1-xAsyP1-y(y=2.1x) between y=0 and y=1 using photoluminescence and electrical measurements

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Abstract
Photoluminescence (PL) and electrical measurements have been made on a series of p-type, Mn-doped layers of GaxIn1-xAsyP1-y (y=2.1x) grown by liquid phase epitaxy on InP substrates and of a similar series of nominally pure crystals used as control samples. For small y, the Mn-doped samples shown an intense Mn-related PL band with a zero-phonon structure at 1.185 eV (4K) for the y=0 (InP) sample. This locates the Mn-acceptor level at 230 meV above the valence band edge. The PL band can be followed up to y=0.40 and the Mn-acceptor energy EA is estimated to vary as (230-185y) meV. For larger y, a broad, though strong, PL is observed on the low energy side of the near-band-edge lines. At these higher y values, electrical measurements have been used to determine EA, giving EA=49 meV for y=0.93 and 0.10 eV for y=0.70, in fairly good agreement with linear extrapolation of the PL data. The low temperature PL of six undoped control samples (0.5<y<1) reveal two sharp PL lines at (1.02-0.33y) and (1.00-0.33y) eV of as yet unknown origin.