Formation of porous nanostructured lead telluride films by an anodic electrochemical etching method

Abstract

Comprehensive research of the structural, optical and electrical properties of a PbTe/CaF 2 /Si(1 1 1) epitaxial system after anodic electrochemical treatment in a Norr solution electrolyte with a low current density of 6 mA cm −2 was carried out. It is shown that the anodizing results in the increase of the band gap and resistivity and in the decrease of the refractive index of lead telluride. Using secondary ion mass spectrometry, a specific change of the C, K, H element distribution in depth of PbTe films after electrochemical treatment was detected. It is demonstrated that the set of presented experimental results can be explained from the standpoint of the formation of a mesoporous structure of lead telluride with a porosity value of about 50%. The effective radius of PbTe nanoparticles is equal to 13 nm. Triple-crystal x-ray diffractometry results analysis showed that the pores have spherical voids with an average dimension of 40 nm.

Investigations of nanostructured porous PbTe films with x-ray diffractometry and reflectometry

“…Given curves are normalized with maximum intensity in the TER region equal to 1. Critical angle for the unanodized sample is slightly smaller than the theoretically calculated value from the film polarizability θ сt = ⎜χ 0 ⎜ 1/2 = 21.83 arcmin, which obviously is explained by the presence of microhillocks on the sample surface that were observed with electron and atomic force microscopy [2]. A considerable decrease of θ с after the anodizing is explained by the decrease of x-ray density due to the pore formation.…”

“…Currently there is a strong demand for an effective method of the fabrication of nanoporous IV-VI semiconductor layers, which have quite an urgent prospects of applying for the new generation optoelectronic and thermoelectric devices. In our recent work [2] we have proposed a new technique of the anodic electrochemical treatment of lead chalcogenide films based on the utilization of initial epitaxial PbTe/CaF 2 /Si(111) systems. Anodizing in a Norr electrolyte [3] with current density j an = 6 mA/cm 2 and with a duration time t = 10 min allowed us to obtain nanostructured porous structures of lead telluride with a nanocrystal dimensions of 26 nm with modified optical and electrophysical properties.…”

Investigations of PbSe layers after anodic electrochemical etching by scanning electron microscopy

“…A vertical type electrochemical cell schematically shown in Fig. 1 was used, which allowed us to perform anodic electrochemical etching of heteroepitaxial multilayered PbSe/CaF 2 /Si(111) structures according to a technique that was previously elaborated and applied for the fabrication of porous PbTe layers [10,11]. Prefabricated teflon base of the cell consists of two main parts: upper unit (1) with a circular platinum cathode and lower unit (2) with flat metallic anode.…”

“…An interesting prospective possibility is to use porous PbX layers as elements of gas analyzers with the extension of already existing technology with a fabrication of high surface to volume ratio of nanostructured material. We have recently developed and reported a technique for the porous structure fabrication based on anodic electrochemical etching of lead telluride epitaxial layers on silicon substrates in a potassium hydroxide based solution [10,11]. The aim of the present work was to carry out anodic treatment for PbSe epitaxial layers under the same anodizing conditions as for PbTe and to compare the obtained results.…”

Fabrication and study of porous PbTe layers on silicon substrates

“…These open possibilities for the development of a variety of new devices. In our recent work [7] we have developed a novel method of lead chalcogenide anodizing based on a treatment of PbTe/CaF 2 /Si(111) structures in a Norr solution [8]. The purpose of the present work was to study porous structure that is formed using this method in lead telluride films at low anodizing current densities compared to conditions used in [7].…”