Growth and Characterization of Telecommunication-Wavelength Quantum Dots Using Bi as a Surfactant

Abstract

Telecommunication-wavelength quantum dots (QDs) were successfully grown by metalorganic vapor phase epitaxy using a novel growth method in which trimethylbismuth (TMBi) was supplied during the growth. Supplying TMBi during the growth was confirmed to have a surfactant effect, but did not result in the formation of a bismuth-containing alloy. Using this growth method, the photoluminescence intensity and wavelength of the QDs were much improved. It was found that the QD size was increased during the growth of the InGaAs covering layer; this effect partly resembled activated alloy phase separation reported for molecular-beam-epitaxy-grown QDs. For the realization of high density and multilayer QDs, we confirmed that a much higher V/III ratio than that of usual growth conditions and a strain-compensation structure are effective, respectively.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…Acting as a surfactant, Bi atoms can smoothen surface and interface of GaAs and its heterostructures during growth. They also reduce point defects and impurities in the matrix, thus decrease non-radiative recombination centers [114] and improve optical properties of the matrix materials. However, incorporation of Bi is usually non-uniform in the matrix, which makes PL quite broad.…”

“…So far there have only been a few studies about Bi's influence on InAs quantum dots (QDs) as summarized in Table 7 [112,114,[251][252][253] while Bi incorporation in nanowires (NWs) has just been reported recently [254]. Owing to δ-like density of states and excellent carrier confinement in QDs, InAs QD lasers possess a number of favorable device performance such as low threshold current density, high temperature stability and large differential gain, making them attractive for high-speed telecom laser applications.…”

“…The second report came by Okamoto et al [114] 10 years later also using MOCVD. This time they designed a dot-in-well structure, i.e., InAs QDs embedded in an InGaAs QW, introducing Bi during both the QDs and QW growth.…”

Increased InAs quantum dot size and density using bismuth as a surfactant

“…[18][19][20] For QD growth, in one case, the use of trimethylbismuth (TMBi) during the metalorganic vapor phase epitaxy (MOVPE) growth of InAs QDs in InGaAs quantum wells (QWs) was found to increase QD uniformity and size without Bi droplet formation or incorporation. 21 Another MOVPE study showed an increase in QD density and a reduction in QD size with the introduction of Bi. 22 For previous MBE-grown InAs QDs, introducing Bi simultaneously with InAs during QD growth resulted in improved QD uniformities, but lowered QD densities.…”

Variation of the photoluminescence spectrum of InAs/GaAs heterostructures grown by ion-beam deposition

“…Then, the QD array density increases. Others argue that the usage of Bi during MOVPE and MBE of InAs QDs [57–58] enhances In adatom diffusion length. In this case, QD sizes increase, and the QD density decreases.…”