A procedure of InAs/InP quantum dots elaboration emitting at 1.55 μm by gas source molecular beam epitaxy is described. It is based on a modification of the capping layer growth which is deposited in two steps, separated by a growth interruption under phosphorus flux. The main effect of this two step capping layer growth is to reduce the height of the biggest islands and thus to decrease the photoluminescence linewidth of the quantum dots emission line. Transmission electron microscopy and photoluminescence experiments show that quantum dots structure are still present after growth interruption under phosphorus flux and that the photoluminescence linewidth at 1.55 μm is reduced from 120 to 50 meV, thanks to this procedure.
International audienceInAs quantum-dot (QD) laser structures are grown on (113)B-oriented InP substrate by gas-source molecular-beam epitaxy. Following an optimized growth procedure, a high density of 1.1×1011 cm−2 of uniformly sized QDs is achieved. Broad-area lasers containing three stacked QD layers have been realized and tested. Laser emission on the ground-state transition (λ = 1.59 μm) is obtained at room temperature (RT), at a threshold current density as low as 190 A/cm2. Ground-state modal gain and transparency current density is measured to be 7 cm−1 and 23 A/cm2 per dot layer. Ground-state laser emission is also demonstrated from low temperature (100 K, Jth = 33 A/cm2) to high temperature (350 K), exhibiting an insensitive threshold in the [100, 170] K range, and a 55 K characteristic temperature at RT
We report on the synthesis of InAs quantum dots on (311)B InP substrates. It is found that the use of such high index surfaces allows the formation of a high density (5×1010 islands/cm2) of small InAs islands (diameter≈350 Å) on InP. Moreover, a large improvement of the size uniformity is obtained in comparison with deposition on (100) surface. The standard height deviations are ±13% and ±50% for islands grown on (311)B and (100) surfaces, respectively. Then, we show that the modification of the As/P flux sequences, after the island formation, permits the control of the quantum dot emission wavelength. The achievement of quantum dots emitting at 1.55 μm at 300 K indicates that this method is promising for telecom device making.
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