Electrical and optical characterizations of self-assembled quantum dots formed by the atomic layer epitaxy technique

Abstract

We investigated the electrical and optical properties of InGaAs self-assembled quantum dots grown using the atomic layer epitaxy (ALE) technique. Dots–in–a–well structures were grown by alternately supplying InAs and GaAs sources on an InGaAs layer and covering with another InGaAs layer. Three samples produced with different numbers of cycles of alternate InAs/GaAs supply were characterized by capacitance-voltage and photoluminescence (PL) measurements. For the ten cycle dots–in–a–well structure, a strong zero-dimensional electron confinement was observed even at room temperature. On the other hand, for the five-cycle structure, the PL results indicate that the InGaAs quantum well structure coexists unstably with premature quantum dots. By comparing the results for samples with different numbers of cycles, we suggest that an ALE dots–in–a–well structure can be formed by the aggregation of In and Ga atoms incorporated into the InGaAs quantum well layer when the number of cycles exceeds the critical number of seven cycles.

Piezomodulated reflectance study of self-assembled InAs quantum dots-in-a-well

“…A lot of studies have been done on the properties of DWELL structure in which quantum dots (QDs) are surrounded by a quantum well [3][4][5][6]. The DWELL structures have superior optical properties to conventional InAs/GaAs QD (CVQD) structures, because the quantum well can enhance the capture rate of carriers to QDs and suppress the thermal escape rate of carriers from QDs at high temperature [7]. It is noteworthy that the two-color (3-5 mm and 8-12 mm) quantum dot focal plane array based on InAs/In x Ga 1Àx As DWELL structure with good performance had been fabricated successfully by Krishna et al [8], and such quantum dots infrared photodetector with dark current densities less than 10 À5 A/cm 2 and peak detectivity as high as 7.1 Â 10 10 cmHz 2 /W at 78 K have also been demonstrated.…”

Incorporation of indium and gallium in atomic layer epitaxy of InGaAs on InP substrates

“…By separately exposing the substrate with individual constituent sources, homogeneous gas-phase reactions are suppressed and adatoms are expected to have enhanced surface mobility [3]. Since its first demonstration of GaAs ALE for III-V materials [4], the ALE method has been widely employed in the growth of nanostructures such as quantum wells (QWs) [5,6], quantum dots (QDs) [7,8], and delta-doped layers [9,10], III-V compound binary semiconductor films for such as GaAs, InAs, InP, GaN, and AlN, as well as the AlGaAs ternary alloy [2,[11][12][13][14][15][16][17]. ALE growth of compound semiconductors using metalorganic (MO) and hydride sources can be readily implemented in a commercial metalorganic chemical vapor deposition (MOCVD) reactor.…”

Lasing characteristics of 1.3-μm atomic layer epitaxy quamtum dot laser diode

“…Since InAs QDs grown by ALE showed enhanced uniformity, suppressed wetting layer effects and relatively larger QD size than the SK-mode QD, ALEmethod has attracted attention on a uniformity problem and a longer wavelength emission above 1.3 µm range [14][15][16] .…”