Low-temperature electrical-transport properties of single-crystal bismuth films under pressure

Abstract

We report an investigation of the low-temperature electrical transport properties of bismuth films under applied hydrostatic pressure. Films with their trigonal axis perpendicular to the film plane and thicknesses of 30, 50, and 500 nm were grown by molecular-beam epitaxy on BaF 2 substrates. At 500 nm thickness the behavior resembles that of bulk Bi. From the observed Shubnikov-de Haas oscillations we find a pressureinduced decrease in extremal Fermi cross section. For the 30-nm film, we obtain the low-temperature carrier densities for electrons and holes together with the corresponding mobilities from magnetoconductance data at pressures up to 20 kbar. We find that pressure strongly reduces the surface-induced excess hole concentration, clearly revealing a finite electron concentration at high pressures. We discuss our results within the context of a possible semimetal-semiconductor transition in thin Bi films.

Structural and magneto-transport properties of electrodeposited bismuth nanowires

“…For example, the pursuit of quantum effects such as the semimetal-semiconductor transition in Bi thin films has continued to attract attention. [14][15][16] To date, most of the Bi nanostructures are in thin film form. However, fabrication of high quality Bi thin films through traditional vapor deposition has proven to be technically challenging.…”

Very large magnetoresistance in electrodeposited single-crystal Bi thin films (invited)

“…11 Due to its unusual electronic properties ͑e.g., very long Fermi wavelength of 400 Å͒ 13 and a long l, Bi is also a unique medium for exploring quantum and ballistic transport properties. [14][15][16] For such studies as well as for capturing the large MR effect for technological purposes, Bi in thin film form is required. Unfortunately, high quality Bi thin films are notoriously difficult to produce.…”

“…Recently, high quality Bi thin films have been produced by molecular beam epitaxy on BaF 2 substrates, a well controlled but slow and costly venture. 16,19 In the last year, we have reported a new method using electrodeposition to fabricate high quality Bi thin films, which exhibit an enormous MR effect. 20,21 Bi has a low melting point of 271.4°C and a rhombohedral structure, which is slightly distorted from a cubic structure.…”

Artificially ordered Bi/Sb superlattice alloys: Fabrication and transport properties

“…They have a small energy overlap between the conduction and valence bands, small effective masses, and high mobilities. Because of these properties, Bi and Sb have frequently been used for quantum confinement studies in quantum well [6][7][8] and quantum wire 9-13 geometries. For small x, the addition of Sb to form Bi 1Ϫx Sb x random alloys decreases the band overlap 14 -23 and results in a transition from semimetal to semiconductor when 0.07рxр0.22.…”