Spontaneous and stimulated photoluminescence on nitrogen A-line and NN-pair line transitions in GaAs1−x Px : N

In accord with recent absorption measurements, photoluminescence measurements on crystals grown from a Ga solution, as well as on some vapor epitaxial crystals, indicate that the A line in GaAs1−x Px : N is higher in energy than formerly believed. Also, the NN-pair emission peak (ENN) has been determined more accurately relative to the A-line peak (EN), and relative to EΓ and Ex. For crystal composition x less than 0.9, only a single NN-pair emission band is observed with ENN = EΓ at x ≈ 0.30. The A-line is broad (⩾ 50 Å) with EN = EΓ at x ≈ 0.40. For EN ≈ EΓ or ENN ≈ EΓ the recombination probability on transitions involving N traps may be resonantly enhanced. If EΓ is close to or degenerate with EN or ENN, carrier reemission from N traps to the conduction band is fast, and stimulated emission involving N or NN trap centers can lead to line narrowing because the excess electron population can readjust rapidly between trap centers and the Γ conduction band.