Micromasking effect and nanostructure self-formation on the surface of lead chalcogenide epitaxial films on Si substrates during argon plasma treatment

Abstract

The surface modification of lead chalcogenide epitaxial films during plasma treatment processes is investigated. With AFM and SIMS measurements it was shown that the mechanism of a microhillock formation is the micromasking effect of dislocation exit sites. Micromasking, and hence microhillock formation, takes place when fluorine sputtered from reactor chamber walls is present on the surface of the films. Micromasks are nucleated at the exits of threading dislocations when low-volatile fluoride compounds are formed due to the reaction of atomic fluorine with Al or Pb accumulated in these areas. The effects obtained are analysed from the standpoint of nanostructure formation, which requires, primarily, the suppression of the micromasking effect. A novel method of fabricating lead chalcogenide nanostructures on Si(1 1 1) substrates via Ar plasma treatment is proposed.

Self-formation of lead telluride nanostructures during argon plasma etching of single-crystal wafers

“…The density of both micro-and nanohillocks depended on the ion energy, with a highest density of large microhillocks not exceeding the density of threading dislocations in the wafer, which typically was (1-2) × 10 8 cm −2 . Formation of such large hillocks can take place due to the micromasking of dislocations, as it was previously systematically observed by us for lead chalcogenide films on silicon and barium fluoride substrates [2]. The density of nanohillocks (figure 1) was typically ~10 9 cm −2 and their formation took place due to redeposition processes on the sputtered surface.…”

“…The grown crystals were cut perpendicular to the growth axis in order to obtain disk wafers with the thickness of 3-5 mm, whose surface was polished with diamond paste with chemical polishing finish. Plasma sputtering (dry etching) of the surface of PbTe(Te) disks was performed using a radiofrequency high-density low-pressure inductively coupled plasma (RF ICP) treatment [2][3][4]. Power applied to the inductor of the plasma reactor was 800 W, RF bias power at the substrate was varied in the range of 100-300 W, self-bias negative potential was 85-195 V, argon flow rate was 10 sccm.…”

Fabrication and characterization of pedestal optical waveguides using TeO2–WO3–Bi2O3 thin film as core layer

“…It was observed that the top of the pedestal structure, has almost no surface roughness. On the other hand, in the lower region of the waveguides, which was subjected to plasma etching, high roughness was observed due to micromasking effect [21]. In fact, during the plasma etching, some chromium particles migrate to the SiO 2 exposed region.…”

Optimum inductively coupled plasma etching of fused silica to remove subsurface damage layer

“…It generally originates from the metallic reactor: metal particles sputtered from the substrate electrode, substrate holder or chamber wall deposit on the substrate surface. And this metal contamination could be a strong PISD initiator [8,16,17] because it could act as a catalytic chain initiator for polymerization [18]. In order to solve this problem, a simple isolation device was employed, see figure 1.…”