Role of Mechanical Stresses at Ion Implantation of CdHgTe Solid Solutions

Abstract

The properties of n-CdxHg1−xTe/CdZnTe (x ≈ 0.223) structures implanted with B + and Ag + ions with an energy of 100 keV to a dose of 3 × 10 13 cm −2 are studied. The software package TRIM_2008 was applied to simulate the ion implantation process. The surface morphology of heterostructures and their optical, mechanical and electrical properties are studied. It is found that the ion irradiation of specimens gives rise to the formation of a characteristic relief on their surface, as well as a layer in the near-surface region, where the optical parameters differ from those in the matrix. The implantation of CdxHg1−xTe epitaxial layers with boron and silver ions with the same energy and to the same dose brings about the formation of a damaged layer, substantially non-uniform by the thickness and the damage character, with maximum mechanical stresses that differ by two orders of magnitude. The values of the crystal lattice contraction coefficient β and the mechanical stresses σmax in the region of radiation-induced disordering in the solid solution are determined. The influence of mechanical stresses in the doped layer on the defect redistribution and the formation of properties of Cd0.223Hg0.777Te after the implantation is discussed.

Ion Beam Nanostructuring of HgCdTe Ternary Compound

“…Besides, reflections attributable to cubic Ag 2 O (2 θ = 32.8°, 38.2° according to ICDD PDF 00-041-1104) are appeared. It should be noted that the simulation of the implantation process performed in [ 25 ] using the TRIM2008 program package allowed us to state that the introduced impurity is mainly localized in the subsurface region (~100 nm) of MCT. The ellipsometry data also indicate the formation, in the silver-implanted CdHgTe/CdZnTe samples, of a distorted ~100-nm-thick layer with anomalous values of the extinction and refractory coefficients [ 25 ].…”

Study of the Morphology of p-CdHgTe Layers Structured by Grazing Silver-Ion Beam Irradiation

“…At the same time, the surface irradiation to the double dose at an angle of 90 ∘ results in a degradation of the CdHgTe film surface. It should be noted that the irradiation of CdHgTe films with boron ions in the same experimental geometry (at the normal incidence of an ionic beam on the surface of specimens), with the same energy, and to the same dose as in the case with silver ions results in a surface damage that is substantially different by the character and the damaged layer thickness [16]. No nanostructuring of the surface is observed in that case.…”

“…No nanostructuring of the surface is observed in that case. The character of CdHgTe crystal lattice distortions is also different: maximum mechanical stresses max in the damaged layer differ by two orders of magnitude, being similar to the squeezing in the case of boron (∼10 3 Pa [16]), and the crystal lattice is stretched (∼10 5 Pa [16]) at the implantation with larger ions (Ag + ) .…”

“…Hence, our research of the influence of the ionic bombardment on the structural properties of -CdHgTe epitaxial films and its dependence on the ionic beam intensity and the incidence angle showed the following. The ionic irradiation of CdHgTe epitaxial films with silver ions at the normal (90 ∘ ) ionic beam incidence on the surface of specimens gives rise to the formation of an array of nanostructures with lateral dimensions from 60 to 120 nm and heights from 12 to 16 nm [16,17]. If the incidence angle of ion beam decreases down to 40 ∘ , the surface nanostructuring gets an ordered character: a two-dimensional quasiperiodic system with the spatial period 1/ = 80÷90 nm is formed.…”

“…At the same time, the morphology and the structuring kinetics are dependent on the angle, at which the ionic flux interacts with the target surface. In our previous works [16][17][18], it was established that the irradiation of CdHgTe films by silver ions resulted in the nanostructuring of their surface and the formation of Ag 2 O in the matrix. This work is aimed at studying the character of changes in the structural properties of the narrow-gap semiconductor compound CdHgTe induced by a variation of the ionic irradiation angle and at analyzing a possibility of the controllable formation of the Ag 2 O--CdHgTe heterostructure on the surface.…”