Optical investigations on isovalent δ layers in III-V semiconductor compounds

Abstract

In contrast to usual quantum wells or barriers having a thickness of some lattice constants, spatially well-separated, electronically uncoupled monolayers of group-III or V elements are considered as isovalent δ doping or δ layers. Similar to the case of randomly distributed nitrogen dopants in GaP bulk material, it is shown that the two-dimensional arrangement of isovalent atoms brings forth a new quality of III-V semiconductor compounds: The optical emission and absorption properties near the fundamental band gap of indirect-gap, and even of direct-gap, host material, where the isovalent layers are incorporated, are drastically improved. Low-temperature luminescence and transmission experiments on metal-organic vapor-phase epitaxially grown InAs δ layers in GaAs, AlAs δ layers in GaAs, and GaAs monolayers in AlAs are dealt with.

Theory of carriers bound to In isoelectronic δ-doping layers in GaAs

“…The strong localization of the HH and the electron explains the high recombination efficiency usually observed in this system. 7 A resonance is found in the conduction band at 1.60 eV. By calculating the DOS projected on the InAs layer and resolving it into its atomic-orbital components it becomes clear that, due to its s character, it is a ⌫ 6 -derived state ͑see Fig.…”

“…[1][2][3][4][5][6][7][8] The controlled growth of such interlayers has allowed us to observe pronounced radiative recombination processes without phonon participation even in indirect-gap materials. 7 The reason for this lies in the recombination efficiency of gap states confined to the impurity layer, which are bound by the short-range potential describing the impurity substitution ͑''␦ layer,'' or ''quantum well''͒.…”

Optical characterization of MOVPE grown δ‐InAs layers in GaAs

“…InAs δ-layers in GaAs matrix reveal extremely high optical recombination efficiency which persists even at elevated temperatures [1]. Embedding InAs δ-layers into the AlGaAs/GaAs waveguide as a laser active region gives an opportunity to produce highly efficient and reliable near infrared lasers.…”

“…During last fifteen years, numerous works have been devoted to structural and optical characterization of submonolayer and supermonolayer InAs quantum wells in GaAs grown by molecular beam epitaxy (MBE) [1,[6][7][8][9]. At the same time, adequate models describing the electronic structure of ultrathin InAs layers based either on quantum-well model [6] or δ-function potential [10] were developed.…”

Chemical and structural effects of two-dimensional isovalent substitutions inA(III)−B(V)semiconductors

“…By photoluminescence, absorption, and reflection measurements it has been shown that the optical properties of a host material can be drastically modified by embedding two-dimensional isovalent substitution layers. [1][2][3][4] Substitution layer/host material systems with efficient excitonic transitions are expected to play a crucial role for next generation optical devices. However, it is an open question how the modifications of the optical properties of the host material depend on the chemical and structural effects associated with the embedded two-dimensional isovalent substitution layer and whether excitons can be effectively bound to the isovalent substitution layer.…”