A. A. Velichko

Effect of high-energy electron beam irradiation on the surface morphology of CaF2/Si(100) heterostructures

The effect of high-energy electron beam irradiation on the surface morphology of CaF2 films in the course of molecular-beam epitaxy on Si(100) substrates is studied by atomic-force microscopy. It is shown that not only do morphological defects significantly change their shape in the electron beam spot, but also their average height more than doubles.

Influence of the surface microroughness of a Si(001) substrate on the morphology of CaF2 epitaxial layers under high-temperature growth conditions

The influence of the surface microroughness of Si(001) substrates on the morphology of CaF2 epitaxial layers is investigated in the high-temperature growth mode. The atomic-force microscopy method is used to demonstrate that the silicon surface relief substantially affects the nucleation, growth, and formation of the morphology of CaF2 layers.

Molecular beam epitaxy of BaF 2 /CaF 2 buffer layers on the Si(100) substrate for monolithic photoreceivers

This paper describes the study of the surface morphology of BaF2 epitaxial films grown by means of molecular beam epitaxy in various growth regimes on a CaF2/Si(100) surface, which is performed by means of atomic force microscopy. The CaF2 layers were obtained on a Si(100) substrate in a low-temperature growth regime (Ts = 500 °C). The technological regimes of growth of BaF2 continuous films with a smooth surface on CaF2/Si(100), suitable as buffer layers for the subsequent growth of PbSnTe layers or other semiconductors, such as A4B6, and solid solutions based on them.

Study of the features of BaF2 heteroepitaxy on CaF2/Si(100) layers obtained in the high-temperature growth mode

The surface morphology of BaF2 epitaxial films grown by MBE (molecular beam epitaxy) in various modes on the surface of CaF2/Si(100) is investigated by AFM. The CaF2 layers on Si(100) are obtained in the high-temperature growth mode (ТS = 750°C). It is shown that the epitaxy of BaF2 at a temperature of 600°C at the initial stage of growth leads to the formation of defects such as perforations in the epitaxial film, while epitaxy at a temperature of 750°C provides a defect-free film with a surface morphology suitable for the subsequent growth of semiconductors of IV–VI type and solid solutions based on them.

Analysis of the oscillation intensity of RHEED specular reflection during the MBE growth of CaF2/Si/CaF2 structures

The results of analysis of the oscillation intensity of RHEED specular reflection during the MBE growth of CaF2/Si(111) structures in a wide temperature range from 100 to 600°С are presented. It is shown that the preliminary formation of a 2D Si buffer layer provides the two-dimensional growth of CaF2 layers. Possible reasons which for the disruption of 2D growth at high substrate temperatures are discussed.

Features of the surface morphology of CaF2/Si(100) films obtained by solid-phase epitaxy

The dielectric parameters of calcium fluoride films grown on the Si(100) surface by solid-phase epitaxy (group 2) and without it (group 1) are analyzed. It is established experimentally that the deposition mode of CaF2 films immediately after growth of the Si buffer layer at a substrate temperature of 530°C is not suitable for producing high-quality dielectric layers. The use of solid-phase epitaxy at the initial stage of the nucleation of CaF2 layers enables the production of single crystal uniformly thick films with high dielectric properties.

Analysis of the temperature instability of an InAs/GaAs heterostructure during the process of molecular-beam epitaxy

It is established that, during the process of the molecular-beam epitaxy of InAs on a GaAs substrate, additional absorption of thermal radiation occurs as the film thickness increases, and, as a consequence, the heterostructure temperature becomes higher than the initial temperature in an uncontrolled way. The nonsteady-state mode of film growth leads to structure degradation. Calculation of the heterostructure overheating makes it possible to adjust the substrate temperature during growth.

Study of RHEED intensity oscillations during the heteroepitaxial growth of CaF 2 on Si(111)

The results of investigations of the nucleation mechanisms and growth of the CaF2/Si(111) heterostructures by reflection high-energy electron diffraction (RHEED) are presented. It is shown that preliminary growth of the 2D silicon buffer layer provides two-dimensional layer-by-layer growth of subsequent layers of CaF2. The possible reasons of the 2D layer-by-layer growth failure at high substrate temperatures are proposed.

Influence of substrate surface morphology on growth CaF 2 on Si (100) in low and high temperature modes

The growth of CaF2 on Si (100) substrates of various qualities was studied for low and high temperature modes at an early growth stages. The growth of samples was carried out by MBE at growth temperature about ~5000°C (low temperature mode) and about ~7500°C (high temperature mode).. The surface morphology of the substrates and the grown structures was studied in semi contact mode with an ambient air Solver P47H NT-MDT atomic force microscope. It was found, that depending on the substrate surface morphology, either triangular shaped CaF2 islands are formed on Si (100) or rectangular shaped CaF2 islands are developed, leaving the most part of a substrate surface uncovered, for low temperature mode. While in high temperature mode on the both types of substrate rectangular shaped CaF2 islands are formed, covering the substrate almost uniformly. In low temperature mode a substrate surface morphology strongly influences morphology of CaF2 films defining formation of structure defects at an initial growth stage.

Electron-beam-induced modification of PbSnTe surface morphology under HEED monitoring of MBE growth

An AFM investigation is conducted into the effect of an electron beam on the surface morphology of PbSnTe films under HEED monitoring of MBE growth. The films are grown on a Si(100) substrate provided with a BaF2/CaF2 buffer. The electron beam is shown to degrade the surface morphology of epitaxial films, changing irregularity shape and size considerably. It is concluded that HEED patterns can be misleading about MBE growth.