Surfactant effect of bismuth in the MOVPE growth of the InAs quantum dots on GaAs

Abstract

We report on the role of bismuth as a surfactant in the growth of InAs quantum dots (QDs) on GaAs (001) by metal organic vapour phase epitaxy. Atomic force microscopy investigations have shown that bismuth suppresses coalescence of the InAs QDs and advances a more uniform size distribution. The photoluminescence spectra of the Bi-assisted grown QDs present several narrow peaks from the ground and the excited state transitions with full width at half maximum (FWHM) as narrow as 25 meV (both at 77 and 300 K). Due to such low values of the FWHM we were able to observe up to two well resolved excited state transitions in the photovoltage spectra measured by an electrolyte cell technique. The lowest ground transition energies observed were 0.93 eV at 77 K and 0.875 eV at 300 K (emission wavelength 1.46 µm). So using Bi-assisted growth it is possible to cover the 1.3 µm band, which is important for optoelectronic applications in the InAs/GaAs material system. Formation of such `deep' QDs without misfit dislocations was explained by the formation of a graded-composition transient InGaAs alloy layer at the GaAs/InAs hetero-interface as a result of diffusion intermixing of the components. The proposed mechanism for the effect of Bi on the QDs' morphology is that Bi decreases the surface mobility of the In atoms on the growing surface, preventing the coalescence of the QDs. Because of its rather large covalent radius (compared with that of As), Bi is not incorporated into the QDs' material segregating on the growing surface.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…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.…”

“…In 2000, Zvonkov et al [251] firstly reported the Bi surfactant effect on InAs QDs grown on GaAs by MOCVD. With Bi supplying during growth, QDs distribute homogeneously with a lateral size and a height much smaller than that of QDs grown without Bi.…”

Гетероструктуры с квантовыми точками InGaAs/GaAs, легированными атомами переходных элементов. I. Фотолюминесцентные свойства

“…Для стабилизации поверх-ности роста КТ и снижения разброса по размерам при-меняется легирование различными примесями. Влияние легирования на особенности самоорганизации КТ иссле-довалось в ряде работ [8][9][10][11]. Модификация механизма формирования КТ вносит контролируемые изменения в их свойства.…”

“…Модификация механизма формирования КТ вносит контролируемые изменения в их свойства. Например, легирование висмутом КТ в про-цессе роста, выполненное в [8], привело к модификации механизма самоорганизации и формированию массива КТ с меньшей шириной спектральной линии. Легиро-вание атомами Mn, выполненное в [10,11], применяется для придания массиву КТ ферромагнитных свойств.…”

Theory and experimental study of surfactant effects on epitaxial growth of compound semiconductors.

“…The surfactant effects of Sb have been studied on GaInP (GaIn)(NAsSb) [16], InGaAs [17], and GaAs [18,19]. B' 1 surfactant effects have been studied on GaInP [7,9], GaAs [19], InGaAs [20,17], InGaNAs [21], Si [22], and during the fabrication of InAs quantum dots [23]. These two surfactants have been reported to modify ordering, composition modulation, dopant incorporation, adatom diffusion, and surface structure.…”