ZnSe∕GaAs(001)heterostructures with defected interfaces: Structural, thermodynamic, and electronic properties

Abstract

We have performed accurate ab-initio pseudopotential calculations for the structural and electronic properties of ZnSe/GaAs(001) heterostructures with interface configurations accounting for charge neutrality prescriptions. Beside the simplest configurations with atomic interdiffusion we consider also some configurations characterized by As depletion and cation vacancies, motivated by the recent successfull growth of ZnSe/GaAs pseudomorphic structures with minimum stacking fault density characterized by the presence of a defected (Zn,Ga)Se alloy in the interface region. We find that-under particular thermodynamic conditions-some defected configurations are favoured with respect to undefected ones with simple anion or cation mixing, and that the calculated band offsets for some defected structures are compatible with those measured. Although it is not possible to extract indications about the precise interface composition and vacancy concentration, our results support the experimental indication of (Zn,Ga)Se defected compounds in high-quality ZnSe/GaAs(001) heterojunctions with low native stacking fault density. The range of measured band offset suggests that different atoms at interfaces rearrange, with possible presence of vacancies, in such a way that not only local charges but also ionic dipoles are vanishing.

Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

“…29 Importantly, the atomistic structure of the interface has a huge impact on band offsets, and can lead to a density of states with metallic character. 28,29 The I-V characteristics of GaAs/ZnSe junctions were shown to be strongly dependent on the growth conditions, and trapping at the GaAs/ZnSe interface could be demonstrated using Raman scattering. 30 Opposite from a flat interface, a unique interfacial composition will be difficult to accomplish in the case of nanocrystals.…”

“…Focusing first instance on the abrupt interface, Kley and Neugebauer noted that the GaAs/ZnSe boundary can be made through either Ga–Se or As–Zn contacts . Compensation is possible through mixed interfaces that involve, for example, mixed (Ga,Zn) or (As,Se) planes or vacancies . Importantly, the atomistic structure of the interface has a huge impact on band offsets and can lead to a density of states with metallic character. , The I–V characteristics of GaAs/ZnSe junctions were shown to be strongly dependent on the growth conditions, and trapping at the GaAs/ZnSe interface could be demonstrated using Raman scattering .…”

Principal physical properties of GaN/AlN multiquantum well systems determined by density functional theory calculations

“…Initially, the existence of a dipole layer at a heterointerface was postulated by Tersoff, 22 the detailed discussion of various heterostructures with the identification of monopole and dipole electric charges was given by Franciosi and Van de Walle. 23 Density functional theory (DFT) calculations were used first to investigate basic physical properties of heterostructures, such as band offsets, etc., by Peressi et al [24][25][26][27] It was found that the strain affects the band offsets of GaAs containing heterostructures drastically. In parallel, identical conclusions were obtained by Picozzi et al for arsenide and anitimonide heterostructures.…”

Efficient Spin Injector Scheme Based on Heusler Materials

“…One of the recent examples is the CoMn 1þx V 1Àx Al and CoFe 1þx Ti 1Àx Al series (0 < x < 0:5) [29] which preserve the half-metallicity within the whole range. In any case, the additional detailed studies of the relative interface stabilities (as, e.g., [40]) including inspection of the various defects will be important for each constructive interface as well.…”