Formation of mid-infrared emissive InAs quantum dots on a graded In_xGa_1−xAs/InP matrix with a more uniform size and higher density under safer growth conditions

Abstract

InAs mid-infrared emissive quantum dots (QDs) grown on a graded InxGa1-xAs/InP matrix with more uniform size and higher dot density have been successfully prepared by low pressure metal organic chemical vapour deposition (LP-MOCVD) under safer growth conditions. Low toxic tertiarybutylarsine and tertiarybutylphosphine sources were used to replace the high toxic arsine and phosphine in the MOCVD growth. To improve the process safety further, inertial N2 instead of the normally used explosive H2 was used as the carrier gas. Initially, by using a two-step growth method, uniform InAs QDs with a high dot density of 1.3 × 10(10) cm(-2) have been successfully grown on a InGaAs/InP matrix. The emission wavelength of the QDs reaches >2.1 µm. The low temperature photoluminescence spectrum of the QDs grown by the two-step growth has much narrower linewidth and higher intensity than that of the QDs grown by using normal Stranski-Krastanow (S-K) and atomic layer epitaxy (ALE) growth methods.

Droplet epitaxy of InAs/InP quantum dots via MOVPE by using an InGaAs interlayer

“…Deposition of indium droplets on In 0.53 Ga 0.47 As and their crystallization into dots [20] or rings [21] have been investigated only in a limited manner under MBE conditions. Studies of InAs QDs growth on graded In 0.53−0.72 Ga 0.47−0.28 As/InP [22] and lattice-matched In 0.53 Ga 0.47 As/InP [23,24] in MOVPE can be also found, where the InAs dots were fabricated by SK [24] or atomic layer epitaxy (ALE) methods [22,23], using N 2 as carrier gas instead of H 2 . To our knowledge, this is the first report of the use of this approach with DE by MOVPE.…”

First-step nucleation growth dependence of InAs/InGaAs/InP quantum dot formation in two-step growth

“…The growth rate, input InAs monolayers and V/III ratio in the first-step growth was kept unchanged at 0.84 ML s −1 , 3.36 MLs and 6.5, respectively, for all five samples. Figure 3 growth as reported in [5]. When the temperature is increased to 520 • C, the nuclei formed in the first-step growth are all developed into QDs during the second-step growth; highdensity QDs, 1.4 × 10 10 cm −2 , have been obtained in sample (g).…”

“…But, InAs/InP QDs grown by using the conventional Stranski-Krastanow (S-K) selfassembly method have difficulties in achieving high dot density and uniform size, and the crystal quality of the QDs grown is also not very good, which limits their applications in developing QD-based devices [1][2][3][4]. Recently, we have developed a two-step growth method for growing high-quality InAs QDs on InP substrate with more uniform dot size and high density [5]. In this two-step QD growth, three-dimensional (3D) island nucleation starts in the first-step growth and is then followed by the kinetic self-limiting growth of uniform QDs in the second-step atomic layer epitaxy (ALE) growth.…”

“…In this two-step QD growth, three-dimensional (3D) island nucleation starts in the first-step growth and is then followed by the kinetic self-limiting growth of uniform QDs in the second-step atomic layer epitaxy (ALE) growth. In 5 Author to whom any correspondence should be addressed.…”

“…previous studies, optimization of the second-step growth has been investigated [5,6]. However, the first-step nucleation has an important impact in the morphology and crystal quality of the QDs finally formed in the two-step growth.…”