High quality InGaAsPInP for multiple quantum well laser diodes grown by low-pressure OMVPE

Abstract

InGaAsP/InP and InGaAs/InGaAsP multiple quantum well (QW) structures were grown by LP-OMVPE. Atomically flat interfaces were demonstrated by growing on (001) InP substrates with different (0.2° and 2°) misorientation. Multiple line photoluminescence (PL) emission at 2 K is observed for the first time from thin QWs which were grown on 0.2° misoriented (001) InP substrates. Corresponding QWs grown on 2° misoriented substrates showed single line PL emission. The multiple line spectra are ascribed to thickness variations within one QW with lateral sizes larger than the excitonic radius. In InGaAsP/InP QWs half-monolayer and in InGaAs/InGaAsP QWS monolayer well width variations were obtained from the analysis of the PL spectra. The studies well thicknesses ranged from 90 Å down to ≈ 4 Å for InGaAsP, with maximum spectral upshifts of 514 meV. The very high quality of the QWs is also indicated by FWHM linewidths of 8.8 meV for a ≈ 6 Å well of InGaAsP and 12.5 meV for a ≈ 10 S̊ well of InGaAs. Two populated subbands were observed for the first time in the two-dimensional electron gas at InP-InGaAsP heterojunctions; a mobility of 80000 cm2/V·s was measured at 30 mK. DCPBH multiple quantum well lasers consisting of 12 InGaAsP wells and 11 InP barriers with threshold currents of 20 mA at an emission wavelength of 1.5 μm were fabricated.