Hole localization energy of 1.18 eV in GaSb quantum dots embedded in GaP

Abstract

Self‐organized GaSb quantum dots are embedded in GaP by molecular beam epitaxy and n+p‐diodes are fabricated. The structure of the sample is investigated using transmission electron microscopy with atomic resolution. The presence of quantum dots on top of a wetting layer and interdiffusion processes between Sb and P are observed. The localization energy, capture cross‐section, and storage time of holes in the ground state of the quantum dots are determined via deep‐level transient spectroscopy. Their localization energy of 1.18false(±0.01false)eV is found to agree with the theoretical prediction of 1.4 eV once the observed interdiffusion is taken into account. A storage time of holes of 3.9false(±0.3false) days at room temperature is calculated, marking an improvement of 3 orders of magnitude from previous record figures. GaSb/GaP quantum dots are, thus, promising candidates for future non‐volatile DRAMs or fast Flash. Schematic representation of the quantum dots (left) and of the valence band in their vicinity (right). The localization energy is marked on the scheme. The localization of the quantum dots prevents thermal emission of holes, generating a storage time at room temperature of 3.9 days.

Structural and compositional analysis of (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots

“…A localization time of 10 6 years was proposed by Marent et al for GaSb/AlAs QDs 36 , but at least 10 years is necessary to reach a practical nonvolatile system. The GaSb/GaP QDs with hole confinement grown by molecular beam epitaxy (MBE) have shown the longest storage time of 4 days 37 . Instead, for QDs grown via metal-organic vapor phase epitaxy (MOVPE), the current storage time for pure In 0.5 Ga 0.5 As/GaP QDs is 230 s at room temperature 38 , while an improvement of one order of magnitude was obtained by adding Sb during the QD growth, leading to a record storage time of 1 h at room temperature, as reported by Sala et al 27 , 39 .…”

Effect of Cap Thickness on InAs/InP Quantum Dots Grown by Droplet Epitaxy in Metal–Organic Vapor Phase Epitaxy

“…Owing to their appealing physical properties, semiconductor quantum dots (QDs) have attracted great attention for a broad range of applications, ranging across lasers and amplifiers, [1][2][3] nanomemories, [4][5][6] and recently as efficient sources of single and entangled photons for quantum information technologies. [7][8][9][10] III-V QDs fabricated by droplet epitaxy (DE) have shown a great degree of flexibility in terms of variety of nanostructures possible and material choice, [11][12][13][14] resulting in improved compositional homogeneity and symmetry, and reduced strain.…”

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

“…The QD-Flash memory concept was suggested and developed by Bimberg et al over a period of 20 years following the first studies by Kapteyn at al. on electron escape mechanism from InAs QDs using the deep level transient spectroscopy (DLTS) [18][19][20][21]. The concept, protected by 16 patents worldwide, attempts to combine the best of both memory worlds, the Dynamic Random Access Memories (DRAM) and the Flash worlds leading to a universal memory, strongly simplifying computer architecture.…”