Selective area growth of InAs quantum dots formed on a patterned GaAs substrate

Abstract

We describe the growth and characterization of InAs quantum dots (QDs) on a patterned GaAs substrate using metalorganic chemical vapor deposition. The QDs nucleate on the ͑001͒ plane atop GaAs truncated pyramids formed by a thin patterned SiO 2 mask. The base diameter of the resulting QDs varies from 30 to 40 nm depending on the size of the mask. With specific growth conditions, we are able to form highly crystalline surface QDs that emit at 1.6 m under room-temperature photopumped conditions. The crystalline uniformity and residual strain is quantified in high-resolution transmission electron microscopy images and high-resolution x-ray reciprocal space mapping. These strained QDs may serve as a template for selective nucleation of a stacked QD active region.

In-situ mask removal in selective area epitaxy using metal organic chemical vapor deposition

“…[17]. Toward this application, we have successfully demonstrated growth of a buried single In 0.20 Ga 0.80 As (120 Å ) QW within Region A.…”

“…We find that a slow growth rate along with a low V/III ratio is necessary to prevent GaAs islanding on the Al x O y layer. For our system configuration, the optimized growth parameters are AsH 3 flow rate ¼ 15 sccm/s, TMG flow rate ¼ 2.1 sccm/s, V/III ¼ 7.5, growth rate ¼ 4 Å /s, which is similar to selective area growth of GaAs on SiO 2 masks [17]. The SAE process results in a 600 nm GaAs layer grown in Region A ( Fig.…”

Selective growth of GaAs nanostructures and subsequent guided self-assembly of InAs quantum dots on nanoimprint lithography patterned SiO2/GaAs substrates

“…4 where AFM topographies of the samples are plotted in two perpendicular directions. The shapes of the pyramids are maintained similar in [0-1-1] direction much longer than in [0][1][2][3][4][5][6][7][8][9][10][11]. This can be explained by the anisotropic surface diffusion of Ga atoms on GaAs(1 0 0) [8]; Ga atoms have much larger diffusion length in [0-11] than in [0-1-1], which leads to elongation of the islands in the [0-11] direction.…”

“…Precise control of the nucleation sites of QDs has gained large interest during the recent years [1,2] and the associated technology is evolving rapidly enabling new approaches to realize practical devices. Selective growth of InAs QDs on directly patterned GaAs substrates has already been demonstrated by various methods [3,4]. Another route to restrict the area where QDs can nucleate is to form a pyramidal island which itself is much larger than a QD, but which provides only small site(s) at which the QDs can nucleate [5].…”

Ordered InAs quantum dots on pre-patterned GaAs (001) by local oxidation nanolithography

“…However, as advanced optoelectronic devices and new applications in nanoelectronics, like logic devices and memories, would clearly benefit from such ordered and precisely situated nanostructures, different approaches have been tried to artificially force QD to self-assemble at predefined sites on pre-patterned substrates [2][3][4][5][6][7][8][9][10]. In this situation, it is vital that the lithographic process used to pre-pattern the substrate will not introduce dislocations, impurities or other point defects at the QD nucleation site in order not to degrade the QD electronic and optical properties.…”