Tuning InP self-assembled quantum structures to telecom wavelength: A versatile original InP(As) nanostructure “workshop”

Abstract

The influence of hydride exposure on previously unreported self-assembled InP(As) nanostructures is investigated, showing an unexpected morphological variability with growth parameters, and producing a large family of InP(As) nanostructures by metalorganic vapour phase epitaxy, from dome and ring-like structures to double dot in a ring ensembles. Moreover, preliminary microphotoluminescence data are indicating the capped rings system as an interesting candidate for single quantum emitters at telecom wavelengths, potentially becoming a possible alternative to InAs QDs for quantum technology and telecom applications.In the past few decades low-dimensional self-assembled quantum dots (QDs), as well as other zero/one dimensional nanostructures, have played an important role in studies of fundamental and applied physics 1 , being attractive, for example, for optoelectronic applications 2, 3 , as well for quantum information and computing 4,5,6 . The possibility to transition/transform from one nanostructure into another is a topic of particular interest, e.g. a dotlike shape can be made into a ring-like one, i.e. into quantum rings (QRs). 7,8,9,10,11,12,13,14,15,16 Considering AlInAs-InP structures, conventionally exploited in telecom applications, they show a peculiar type II band alignment, making them suitable for conventional opto-microelectronics 17 , while can also be an attractive option for "exotic" innovative applications with engineered band alignment. Some of us have shown unforeseen evidence 18 that the presence of Al0.48In0.52As, together with specific surface organization (and possible phase separation), has profound effects on the nucleation of InP (mono)layers. Indeed, InP deposited directly on lattice-matched AlInAs forms a variety of nanostructures, despite the nominally strain free environment. These structures, if capped, would generally result in a relatively broad type II emission around one micron, while preliminary transmission microscopy images show that the nanostructures evolve during capping, and are partially preserved after overgrowth. 19In this Letter, we report on the possibility of transforming these InP nanostructures grown by metalorganic vapour phase epitaxy (MOVPE) on lattice-matched InP substrates into variously shaped InP(As) emitters in the telecom windows. For example, InP(As) dots-to-rings transformation is carried out by intentional exposition to selected hydrides. Moreover, we observe a large phenomenology of a) Author to whom correspondence should be addressed. Electronic mail: enrica.mura@tyndall.ie 2 morphologies induced by growth conditions choice and post-growth layer exposure to hydrides that we critically discuss. Indeed the combination of arsenisation and cooldown protocols affects the final nanostructures' shape, changing the original dots into rings or domes (and others), conveying a rich variety of nanostructures in a controlled manner, and importantly engineering the photoluminescence characteristics, with specific configurations delivering clear signatu...

Excitonic lasing of strain-free InP(As) quantum dots in AlInAs microdisk

“…From TEM data presented in Supplementary Materials (SM) we found that, in the structures having thin caps, the QDs were only slightly modified and had slightly reduced height (down to 5 nm from the ~8 nm in uncapped samples) and increased size (up to 300 nm). This indicates some form of "melting" of these NPC QDs and a planarization of the InP deposit induced by capping, at least with the here discussed growth conditions, with non-continuous areas of a "wetting layer" like structure too 31.…”

“…This indicates some form of "melting" of these NPC QDs and a planarization of the InP deposit induced by capping, at least with the here discussed growth conditions, with non-continuous areas of a "wetting layer" like structure too. 31 In the cross-section TEM images (see Fig. 1a) the InP deposit in MD structure are seen as a white broken stripe having thickness of ~2 nm, which represent nanopan-cake (NPC) shape QDs having density of ~5x10 17 cm -3 silicon doping of 20 nm part of AlInAs at distance of 20 nm from QDs.…”

Comparison of InGaAs and InAlAs sacrificial layers for release of InP-based devices

“…The overgrowth of the InAlAs layer commenced with a thin (10 nm) InGaAs layer to avoid aggregation issues and improve morphology of the InP [16,17]. Rectangular and circular coupons ranging from 40 µm to 400 µm in width and 50 µm to 500 µm in diameter are realized.…”

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

“…The In x Ga 1− x Sb deposition on AlP can, in general, result in the In x Ga 1− x Sb y P 1− y /AlP SAQDs formation. The material intermixing can occur during the III-Sb deposition stage due to bulk interdiffusion [ 47 , 48 , 49 , 50 ], as well as during the growth of cap AlP layers due to the material segregation and exchange reaction between the SAQD and the AlP matrix [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. In order to simplify calculations, we considered SAQDs consisting of quaternary alloys Ga x Al 1− x Sb y P 1− y , In x Al 1− x Sb y P 1− y and In x Ga 1− x Sb y P 1− y .…”