Semimetal to semiconductor transition in ErP islands grown on InP(001) due to quantum-size effects

Abstract

Thickness-dependent changes in the electronic states of semimetal ErP islands grown on the InP͑001͒ surface by organometallic vapor-phase epitaxy have been investigated by means of scanning tunneling microscopy/spectroscopy. The normalized differential conductance spectra show a semimetal behavior for the ErP islands ͑20-50 nm in size͒ with thickness larger than 3.4 nm, while the spectra taken for the islands thinner than 3.4 nm reveal a semiconducting gap varying to ϳ1 eV. The thickness dependence of the observed gap is explained by the energy gap between the electron sublevel and the hole sublevel calculated using a one-dimensional square-well potential model with infinite barriers. The results demonstrate a semimetal to semiconductor transition due to the quantum size effect on the semimetal ErP band structure with a band overlap of Ϫ0.3 eV.

Spectroscopic ellipsometry and polarimetry for materials and systems analysis at the nanometer scale: state-of-the-art, potential, and perspectives

“…In particular, it is shown that ellipsometry can also be sensitive to effects of oxygen vacancies on the optical functions. In fact, nanostructured CeO 2 is reported to exhibit a lower fundamental gap than crystalline CeO 2 , although the quantum-size effects are expected to induce a blueshift of the band gap (Kim et al 2002 ; Bolotov et al 1999 ), as also seen in the previous paragraph. It has already been reported that nanostructured CeO 2 mainly consists of CeO 2 nanocrystals or nanorods, with a considerable concentration of trivalent Ce 3+ distributed at the outermost surface of the nanocrystals or nanorods (Losurdo 2004 ).…”

Langmuir Nanoarchitectonics: One-Touch Fabrication of Regularly Sized Nanodisks at the Air–Water Interface

“…Additionally, the restriction of structure to a 2D plane converts extended quantum wells to size-controlled quantum disk objects whose thickness is a few nanometers, perhaps leading to quantum effects orthogonal to the object plane and confined in-plane effects when widths are between 10 and 100 nm. For example, a phase transition from half-metal to semiconductor for ErP quantum disks can be induced by reducing their thickness to less than 3 nm . Also, the regulation of vector magnetism in two dimensions within magnetic disks of diameters of ca.…”

Theory of magnetoresistance in ferromagnetic junctions with a semimetal

“…The FM tunnel junction is a promising candidate of MRAM elements. However, lower resistance and higher magnetoresistance (MR) ratio are required for the application.Recently, quantum size effects on the electronic states of quantum dots of ErP grown on a semiconducting InP substrate have been reported by STM measurements [3]. It has been shown that semimetallic character of electronic states in bulk ErP changes to semiconducting one with decreasing size of the ErP dot.…”