Selective MOCVD growth of single-crystal dense GaAs quantum dot array using cylinder-forming diblock copolymers

One-dimensional aligned InAs/InP quantum dots chain growth by metalorganic vapor phase epitaxy for 1.55μm application

“…In previous reports of the position controlled InAs QDs growth by various methods in different substrates, single dot or single line of dots was grown in the window area if the spacing is smaller than 100 nm while many dots were randomly distributed for the case of a larger window area [9,11,15]. The dot is not in a pyramid shape but elongated or coalesced along the grating direction of [1][2][3][4][5][6][7][8][9][10], as typical observed in InAs grown on InP [16,17]. The lateral size in the [1 1 0] direction is in the range of 30-40 nm.…”

“…Selective epitaxial growth of QDs in patterned dielectric templates provides a way to grow QDs in pre-defined areas. It has been demonstrated that individual QD can be grown in two-dimensional hole patterns in oxide film [8,9] or in the porous substrate formed by anodic aluminum oxidation and etching [10]. There are also reports of growing QDs in a one-dimensional strip using the dielectric template [11,12].…”

Selective MOCVD growth of InGaAs/GaAs and InGaAs/InP quantum dots employing diblock copolymer nanopatterning

“…The general block copolymer nano-patterning process consists of a series of pattern-transfers from a dense array of nanosized holes in diblock copolymer thin film to a dielectric template mask, allowing the patterned access to the GaAs substrate during selective growth [25]. SiO 2 (2 nm) / GaAs and SiN x (10 nm) / InP substrates were initially pretreated with hydroxy-terminated PS-r-PMMA random copolymer brush material with 57 vol % of PS synthesized by radical polymerization.…”

Controlled growth of InGaAs/InGaAsP quantum dots on InP substrates employing diblock copolymer lithography

“…Nanopatterning combined with etching/selective growth processes have been explored as alternative methods for lowdimensional nanostructure fabrication. [4][5][6][7][8][9][10][11][12][13][14][15] The challenges facing QD nanofabrication include the ability to pattern large surface areas, allowing for device implementation, and the reduction of surface states to obtain high optical quality material ͑i.e., low nonradiative recombination͒. Previous studies employing electron beam lithography [6][7][8][9] or atomic force microscopy oxidation 10 for QD nanopatterning are relatively slow, and as a result, high cost processes, inhibiting their use for large area device structures.…”

“…Using this approach, we have previously demonstrated that GaAs QDs with a 12 nm diameter peak distribution and high density, e.g., ϳ5.5-6.9 ϫ 10 10 / cm 2 , which is comparable to self-assembled QDs, can be achieved employing cylinder-forming diblock copolymer lithography and selective MOCVD growth. 12 Higher growth temperatures, compared with that necessary for selfassembled QD growth, can be employed, which is expected to lead to a reduction in the nonradiative centers within the QD material. Since the SK self-assembly process is not employed, the problematic wetting layer states are eliminated and improved optical gain is expected.…”