Molecular Beam Epitaxy Method Research Articles

Single crystal growth of topological semimetals and magnetic topological materials

Topological materials have attracted much attention due to their novel physical properties. These materials can not only serve as a platform for studying the fundamental physics, but also demonstrate a significant potential application in electronics, and they are studied usually in two ways. One is to constantly explore new experimental phenomena and physical problems in existing topological materials, and the other is to predict and discover new topological material systems and carry out synthesis for further studies. In a word, high-quality crystals are very important for studying quantum oscillations, angle resolved photoemission spectra or scanning tunneling microscopy. In this work, the classifications and developments of topological materials, including topological insulators, topological semimetals, and magnetic topological materials, are introduced. As usually employed growth methods in growing topological materials, flux and vapour transport methods are introduced in detail. Other growth methods, such as Bridgman, float-zone, vapour deposition and molecular beam epitaxy methods, are also briefly mentioned. Then the details about the crystal growth of some typical topological materials, including topological insulators/semimetals, high Chern number chiral topological semimetals and magnetic topological materials, are elaborated. Meanwhile, the identification of crystal quality is also briefly introduced, including the analysis of crystal composition and structure, which are greatly important.

Single crystal growth of topological semimetals and magnetic topological materials

Topological materials have attracted much attention due to their novel physical properties. These materials can not only serve as a platform for studying the fundamental physics, but also demonstrate a significant potential application in electronics, and they are studied usually in two ways. One is to constantly explore new experimental phenomena and physical problems in existing topological materials, and the other is to predict and discover new topological material systems and carry out synthesis. In a word, high-quality crystals are very important for studying quantum oscillations, angle resolved photoemission spectra or scanning tunneling microscopy. In this work, the classifications and developments of topological materials, including topological insulators, topological semimetals, and magnetic topological materials, are introduced. As usually employed growth methods in growing topological materials, flux and vapour transport methods are introduced in detail. Other growth methods, such as Bridgman, float-zone, vapour deposition and molecular beam epitaxy methods, are also briefly mentioned. Then the details about the crystal growth of some typical topological materials, including topological insulators/semimetals, high Chern number chiral topological semimetals and magnetic topological materials, are elaborated. Meanwhile, the identification of crystal quality is also briefly introduced, including the analysis of crystal composition and structure, which are greatly important.

Crystalline and optoelectronic properties of Ge1−x Sn x /high-Si-content-Si y Ge1−x−y Sn x double-quantum wells grown with low-temperature molecular beam epitaxy

In this study, we investigated the impact of the growth temperatures of molecular beam epitaxy method for the Si y Ge1−x−y Sn x barrier with a Si content over 20% of Ge1−x Sn x /Si y Ge1−x−y Sn x single-quantum well (QW) on their crystalline and photoluminescence (PL) properties. As a result, we found that lowering T SiGeSn down to 100 °C achieves the superior crystallinity and the higher PL efficiency at room temperature. It was owing to the suppression of the Sn segregation according to the surface morphology observation. Based on this finding, we realized the epitaxial growth of Ge1−x Sn x /Si y Ge1−x−y Sn x double-QWs at 100 °C. We verified the superior crystallinity with the abrupt interface by x-ray diffraction and scanning transmission electron microscopy. In this study, we discussed the optical transition mechanism of the single- and double-QWs based on the band alignment simulation. Finally, we found that the double-QW grown at 100 °C can sustain its crystalline structure against annealing at the N2 atmosphere up to 350 °C, and the PL performance can be also improved by the thermal treatment at around 350 °C.

First-principle study on the effect of S/Se/Te doping and VZn-Hi coexistence on ZnO electrical conductivity

Abstract In a vacuum environment, when ZnO is prepared using the chemical vapor deposition method and the molecular beam epitaxial growth method, H-gap impurities inevitably remain in the ZnO system, which is often ignored. The study of Zn vacancies under experimental conditions poses a challenge. Second, as an n-type semiconductor, ZnO is characterized by a self-compensation of natural donor defects and poor stability, which severely limit the acquisition of p-type ZnO. Based on the above problems, the conductive properties of S/Se/Te doped and VZn-Hi coexisting ZnO were investigated by first principle to acquire high-stability and high-quality p-ZnO. The study found that Zn35SO35, Zn35SeO35, and Zn35SHiO35 all have good p-type conductivity, which can effectively improve hole mobility and electrical conductivity. Among them, Zn35SO35 has the largest hole concentration at 2.80×1021 cm−3, as well as the best conductivity. The choice of Zn35SO35 provides a reference for obtaining new high-quality p-type ZnO semiconductors.

Modelling of diffraction of X-rays in perovskite superlattices

Nowadays, different perovskite structures are widely investigated because they can be potentially used in many branches of industry. If two materials are deposited alternately on a substrate, then a superlattice having some unique properties can be formed. However, X-ray intensity distributions for perovskite superlattices, especially for very thin films, are difficult to be computationally determined, because many different parameters need to be considered to reproduce a superstructure of a sample. The main purpose of this work is to demonstrate how basic intensity distributions can be generated for perovskites, XRD technique and how to improve results using specific numerical methods. The computer application with a user-friendly graphical interface has been developed employing Unity software (with 3D graphics tools) and Oracle Database (through Oracle Cloud Infrastructure). The calculations are based on the kinematical theory of diffraction. The values of some important parameters and the results are stored in the assigned database. It is assumed that epitaxial superlattices can be prepared on substrates using molecular beam epitaxy or pulsed laser deposition methods. The desktop application allows for designing samples of different thicknesses and combinations of monolayers. The results are more realistic if Monte Carlo simulations are done although longer computation time is required. The software developed should be helpful to compare in detail virtual model results with experimental data.

Atomic Magnetic Heating Effect Enhanced Hydrogen Evolution Reaction of Gd@MoS2 Single-Atom Catalysts.

Atomic heating on single atoms (SAs) to maximize the catalytic efficiency of each active site would be a fascinating solution to break the bottleneck for the performance improvement of single-atom catalysts (SACs) but highly challenging task. Here, based on the Gd@MoS2 SACs synthesized by a facile laser molecular beam epitaxy method, high-frequency alternating magnetic field (AMF) technology is employed to induce atomic magnetic heating on Gd SAs that is meanwhile demonstrated to be the catalytic active center. Significant improvement in catalytic kinetics under AMF excitation (3.9 mT) is achieved, yielding a remarkable enhancement of hydrogen evolution reaction magnetothermal-current by ≈924%. Through theoretical calculations and spin-related electrochemical experiments, such promotion in catalyst activity can be attributed to spin flip (or canting) in Gd SAs leading to the atomic magnetic heating effect on catalytic active center. Together with the embodied high stability, the implement of AMF to the SAs field is demonstrated in this work, and the precisely atomic magnetic heating on specific SAs offers unprecedented thinking for further improvement of SACs performance in the future.

Overcoming metal-rich surface chemistry limitations of ScAlN for high electrical performance heterostructures

While metal-rich ScAlN epitaxy has traditionally led to mixed phase films by controlling the surface chemistry with transient metal doses utilizing a pulsed method of molecular beam epitaxy, phase-pure, metal-rich epitaxy of ScAlN was demonstrated, showing improved structural and electrical characteristics. The effects of substrate temperature and III/V ratio were studied, and an x-ray diffraction figure of merit and surface roughness as low as 225 arcsec and 0.68 nm, respectively, were demonstrated. A significant catalytic effect is observed with the use of Sc in metal-rich conditions, resulting in varied growth rates with substrate temperature and Sc surface coverage. This catalytic effect results in complications when selecting synthesis conditions and for in situ monitoring and can be accounted for improved phase purity. The variation of growth rates with Sc surface coverage introduces non-linearities to the transient initiation stage of growth but also introduces a feedback stabilization of the surface chemistry. Accounting for these complexities, a Sc0.2Al0.8N high electron mobility transistor (HEMT) heterostructure is demonstrated with a sheet resistance of 152 Ω/□, a mobility of 700 cm2/Vs, and a sheet charge of 5.9 × 1013 cm−2.

Spin-polarization of topological crystalline and normal insulator Pb[formula omitted]Sn[formula omitted]Se (111) epilayers probed by photoelectron spectroscopy

The helical spin texture on the surface of topological crystalline insulators (TCI) makes these materials attractive for application in spintronics. In this work, spin-polarization and electronic structure of surface states of (111)-oriented Pb1−xSnxSe TCI epitaxial films are examined by angle- as well as spin-resolved photoemission spectroscopy (SR-ARPES). High-quality epilayers with various Sn content are grown by the molecular beam epitaxy (MBE) method. Topological-normal insulator transition manifesting itself as band gap opening is observed. It is shown that the gap opening can be induced not only by changing the Sn content of the epilayer but also depositing a transition metal (TM) on its surface. In the latter case, the observed gaping of the surface states is caused by change in surface composition and not by magnetism. We also show that helical spin polarization is present not only for samples of topological composition but also for trivial ones (with an open band gap). The observed spin polarization reaches a value of 30% for the in-plane spin component and is almost absent for the out-of-plane one. We believe that our work will pave the way for the application of surface states not only of topological but also normal insulators based on lead–tin chalcogenides in spin-charge conversion devices.

Photoluminescence of Europium in ZnO and ZnMgO thin films grown by Molecular Beam Epitaxy

In this work, luminescence properties of Europium doped ZnO and ZnMgO thin films grown on a-oriented (11–20) sapphire substrates by oxygen plasma assisted Molecular Beam Epitaxy method are studied. The concentrations and distributions of Eu atoms in the respective hosts were analysed using Secondary Ion Mass Spectrometry, which confirmed successful doping around the level of ∼1%. Optical properties of the samples were investigated by room temperature photoluminescence (PL) and Photoluminescence excitation (PLE) measurements. The PL data suggest the co-existence of 2+ and 3+ ionic states of Eu in the as-grown samples. It has been observed that alloying Mg with ZnO increases the intensity of the 5D0→7FJ intra-4f-shell emission of Eu3+ ions by an order of magnitude even in as-grown samples. The samples were also annealed at 800 °C in oxygen flux and re-measured to see changes in the PL. After annealing, all the emission lines due to the 5D0→7FJ intra-4f-shell transitions of Eu3+ were strongly enhanced, whereas the bands attributed to Eu2+ were found to diminish or disappear completely. The results of PLE measurements point to efficient host to dopant energy transfer in the studied films.

Crystallization Of Tensile Strained n-Type Ge By Continuous Wave Laser Annealing

In recent years, germanium (Ge) has attracted a lot of attention for the development of next generation devices due to its higher carrier mobilities compared with silicon (Si) and its compatibility for complementary metal-oxide-semiconductor (CMOS) applications. It is widely known that Ge is an indirect-band semiconductor like Si. However, by introducing tensile strain, the 136 meV difference between direct and indirect gaps can be reduced. Furthermore, in the case of 0.2-0.3% tensile strained Ge, n-type doping in the order of 1019 cm-3 were expected to be resulted in quasi direct-band light emission around 1550 nm wavelength. [1] The realization of this tensile strained n-Ge is promising for the integration of light sources on next generation Ge-based devices. Here, we focused on n-type Ge deposition using molecular beam epitaxy (MBE) method and have succeeded in realizing highly Sb-doped epitaxial n-Ge films by modulating the deposition temperatures. [2] Moreover, we have recently reported the crystallization of amorphous Ge by high-speed continuous wave laser annealing (CWLA), which more importantly also resulted in the introduction of 0.55-0.62% tensile strain. [3] In this study, we applied the similar annealing technique for crystallization of Sb-doped Ge toward the realization of tensile strained n-type Ge films.Sb-doped poly-crystalline Ge films with high Sb concentration (approximately 1019 cm-3) and thickness of about 100 nm were deposited on quartz substrate by molecular beam deposition at 450ºC substrate temperature. Then, 300 nm of SiO2 capping layer was deposited by sputtering in room temperature, such that the sample structure become that shown in Fig.1(a). The samples then annealed in the CWLA system equipped with Nd:YVO4 solid state laser with wavelength of 532 nm as the light source, which scan laser light at the speed (vscan) of 800 m/min. Also, the laser is focused to 20 μm diameter and shifted at 5 μm to scan the samples. Here, the laser power (Elaser) was changed from 300 to 1000 mW. After laser annealing, the capping layer were removed then the samples were characterized by micro-Raman spectroscopy.The annealed sample surface shows brighter contrast compared to the as-deposited samples, as shown in Fig.1(b) and (c), which indicate the structural change of Ge layer. Raman spectra measured at surface of annealed Ge layers are summarized in Fig.2. Here, Ge-Ge peak around 300.2 cm-1 confirmed on the samples, indicating the crystallization of the Ge layers. This peak is not shifted in low Elaser but largely shifted in high Elaser at up to -2.4 cm-1 for undoped and -3.6 cm-1 for the Sb-doped Ge films. This difference could be explained by the liquid phase recrystallization after Ge layer melted in high Elaser (≥600 mW). During recrystallization process, tensile strain is accumulated upon cooling as the tensile strain amount (0.43-0.63%) is agree with the thermal expansion value of Ge between solidification temperature and room temperature (-0.60%). This mechanism is similar to the crystallization of amorphous Ge films on quartz substrates in our previous work. [3] These results show the successful crystallization of tensile strained n-Ge layer by the CWLA method. This finding will be useful for the growth of Ge-based films and a promising step toward the development of CMOS-integrated optoelectronics. Further investigation of the annealing conditions and its relations with the properties of Sb-doped Ge films will be discussed in the main presentation. References Liu, J., Kimerling, L. C. & Michel, J. Semicond. Sci. Technol. 27, (2012).Saputro, R.H., Matsumura, R. & Fukata, N. Cryst. Growth & Des. 21, 6523–6528 (2021).Matsumura, R. & Fukata, N. ECS J. Solid State Sci. Technol. 9, 063002 (2020). Figure 1

Single-Element 2D Materials beyond Graphene: Methods of Epitaxial Synthesis.

Today, two-dimensional materials are one of the key research topics for scientists around the world. Interest in 2D materials is not surprising because, thanks to their remarkable mechanical, thermal, electrical, magnetic, and optical properties, they promise to revolutionize electronics. The unique properties of graphene-like 2D materials give them the potential to create completely new types of devices for functional electronics, nanophotonics, and quantum technologies. This paper considers epitaxially grown two-dimensional allotropic modifications of single elements: graphene (C) and its analogs (transgraphenes) borophene (B), aluminene (Al), gallenene (Ga), indiene (In), thallene (Tl), silicene (Si), germanene (Ge), stanene (Sn), plumbene (Pb), phosphorene (P), arsenene (As), antimonene (Sb), bismuthene (Bi), selenene (Se), and tellurene (Te). The emphasis is put on their structural parameters and technological modes in the method of molecular beam epitaxy, which ensure the production of high-quality defect-free single-element two-dimensional structures of a large area for promising device applications.

Single-crystal thin film growth of the Mott insulator EuVO3 under biaxial substrate strain

We report the single-crystal thin film growth of EuVO3 of a Mott insulator with V3+ (d2,S=1). We used the pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) methods and obtained the well-oriented epitaxial thin films with a pseudo-tetragonal crystal structure of EuVO3 which is distinct from the orthorhombic structure in bulk. The high quality of EuVO3 films is verified by the valence state of europium and vanadium ions with X-ray absorption near-edge structure (XANES) measurements showing clear signs from Eu3+ and V3+. The electrical resistivity exhibits the insulating temperature dependence; however, the magnitude of the resistivity is reduced from that of bulk EuVO3, possibly due to biaxial strain from substrates.

Ultrathin TiN Epitaxial Films as Transparent Conductive Electrodes.

Titanium nitride (TiN), a transition-metal compound with tight covalent Ti-N bonding, has a high melting temperature and superior mechanical and chemical stabilities compared to noble metals. With a reduction in thickness, the optical transmittance of TiN films can be drastically increased, and in combination with its excellent electrical conductivity, the ultrathin and continuous TiN film can be considered as an ideal alternative of the metal oxide electrodes. However, the deposition of ultrathin and continuous metallic layer with a smooth surface morphology is a major challenge for typical deposition methods such as thermal evaporation or reactive sputtering. In particular, defects mainly related with oxygen contents and surface scattering can significantly limit the performance of ultrathin TiN films. In this work, ultrathin TiN films with 2-10 nm in thickness are grown by using the nitrogen plasma-assisted molecular-beam epitaxy (MBE) method in an ultrahigh vacuum environment. Excellent surface morphology with a root-mean-square roughness of ≤0.12 nm and a high optical transparency of 75% over the whole visible regime are achieved for ultrathin TiN epitaxial films. The dielectric properties determined by the spectroscopic ellipsometry and the electrical properties measured by the terahertz spectroscopy and the Hall effect method reveal that the percolation thickness of the TiN epitaxial film is less than 2.4 nm and its electrical conductivity is higher than 1.1 × 104 Ω-1 cm-1. These features make MBE-grown ultrathin TiN epitaxial films a good candidate for robust, low cost, and large-area transparent conductive electrodes.

Recent Developments of Quantum Dot Materials for High Speed and Ultrafast Lasers.

Owing to their high integration and functionality, nanometer-scale optoelectronic devices based on III-V semiconductor materials are emerging as an enabling technology for fiber-optic communication applications. Semiconductor quantum dots (QDs) with the three-dimensional carrier confinement offer potential advantages to such optoelectronic devices in terms of high modulation bandwidth, low threshold current density, temperature insensitivity, reduced saturation fluence, and wavelength flexibility. In this paper, we review the development of the molecular beam epitaxial (MBE) growth methods, material properties, and device characteristics of semiconductor QDs. Two kinds of III-V QD-based lasers for optical communication are summarized: one is the active electrical pumped lasers, such as the Fabry–Perot lasers, the distributed feedback lasers, and the vertical cavity surface emitting lasers, and the other is the passive lasers and the instance of the semiconductor saturable absorber mirrors mode-locked lasers. By analyzing the pros and cons of the different QD lasers by their structures, mechanisms, and performance, the challenges that arise when using these devices for the applications of fiber-optic communication have been presented.

MBE grown preferentially oriented CdMgO alloy on m- and c-plane sapphire substrates

Unlike other II-VI semiconductors, CdO-based transparent oxide has great potential application for the fabrication of many optoelectronic devices. In this work, we study the growth of CdxMg1-xO alloys on m- and on c-plane sapphire substrates in Cd-rich to Mg-rich conditions using the plasma-assisted molecular beam epitaxy method. A structural and morphological study of CdMgO random alloys was carried out using X-ray diffraction and Atomic Force Microscope (AFM) techniques whereas composition analysis was done by Energy-dispersive X-ray (EDX) spectroscopy method. The optical properties of thin films were investigated by UV–Vis spectroscopy at room temperature. X-ray analysis confirmed the presence of cubic rock salt structure with <111> CdMgO crystallographic orientation on c-plane sapphire and <110> CdMgO preferential orientation on m-plane sapphire. The surface roughness was measured by the AFM. From the absorption curve, the optical bandgaps were determined using Tauc relation and it was found that the bandgap of films is influenced by the incorporation of Mg2+ ions into the CdO lattice. Bowing parameter was calculated for both samples on m- and c-sapphires.

Epitaxial Growth of Bi2Se3 Infrared Transparent Conductive Film and Heterojunction Diode by Molecular Beam Epitaxy.

Epitaxial n-type infrared transparent conductive Bi2Se3 thin film was cultivated by molecular beam epitaxy (MBE) method on Al2O3 (001) substrate. The orientation between Bi2Se3 and the substrate is Bi2Se3(001)//Al2O3(1 10). Conducting mechanism ensued the small-polaron hopping mechanism, with an activation energy of 34 meV. The film demonstrates conductivity of n-type, and the resistivity is 7 × 10−4 Ωcm at room temperature. The Film exhibits an excellent carrier mobility of 1,015 cm2/Vs at room temperature and retains optical transparency in the near-infrared (>70%) and far-infrared (>85%) ranges. To the best of our knowledge, the Bi2Se3 film yields the best result in the realm of n-type Infrared transparent conductive thin films generated through either physical or chemical methods. To demonstrate the application of such films, we produced N-Bi2Se3/P-CuScO2 heterojunction diode device, the ∼3.3 V threshold voltage of which conformed fairly well with the CuScO2 bandgap value. The high optical transparency and conductivity of Bi2Se3 film make it very promising for optoelectronic applications, where a wide wavelength range from near-infrared to far-infrared is required.

Nonlinear saturable properties of indium selenide film fabricated by molecular beam epitaxy method in near infrared region and Q-switched laser performance for Nd:GdYNbO laser

Two-dimensional layered materials have caught considerable attention for their intrinsic value. Much effort has been made to excavate novel 2D materials with more distinctive characteristics as optical modulators. Single-crystal indium selenide (In2Se3) film with few layers fabricated by molecular beam epitaxy method, for the first time, is employed in this study as a saturable absorber for an Nd3+ doped Gd:GdYNbO infrared laser. Our experimental results demonstrate that the high-quality In2Se3 film achieves a desirable modulation depth of 18.4%, but only 5.9% for the LPE one. The shortest pulse duration and maximum single pulse energy of In2Se3 film are both much better than those of MoS2 and WS2 films in the same laser system. It further confirms the distinguishing properties of the MBE-growth In2Se3 film for optical modulation in infrared region.

Формирование методом молекулярно-пучковой эпитаксии с плазменной активацией азота гетероструктур с множественными квантовыми ямами InN/InGaN на сапфире

The features of the process of growth of multilayer heterostructures with InN/InGaN quantum wells (QWs) by the method of molecular-beam epitaxy with nitrogen plasma activation in the mode of modulated metal fluxes are studied. To compensate for elastic stresses in the structure, the active region was formed in the form of an InN/InGaN superlattice matched over the average lattice parameter with the underlying InGaN buffer layer. It has been shown that during the growth of relatively narrow InN QWs up to 3 nm wide, there is no relaxation of elastic stresses in the active region of the structure, and the dislocation density remains at the level ND ∼ (3−4) · 10^10 cm−2, which corresponds to the dislocation density in InGaN buffer. Such structures demonstrate the most intense PL in the wavelength range of 1.3−1.5 µm. With the growth of wider QWs, the imperfection of the structures sharply increases (ND &gt; 10^11 cm−2), which is accompanied by a decrease in the emission intensity. The structures grown with InN/InGaN QWs demonstrated an order of magnitude better temperature stability of PL compared to bulk InN layers (PL quenching by ∼ 3 and ∼ 25 times, respectively, in the temperature range of 77−300 K). Nevertheless, at a low temperature (T = 77 K), the PL intensity of the studied structures with InN/InGaN QWs is noticeably inferior to that for the bulk InN layer, which apparently indicates a significant role of nonradiative recombination by the Shockley−Reed−Hall mechanism in structures with QWs (as opposed to Auger recombination in bulk InN).

Formation of heterostructures with multiple quantum wells InN/InGaN by the PA-MBE method on sapphire

The features of the process of growth of multilayer heterostructures with InN/InGaN quantum wells (QWs) by the method of molecular-beam epitaxy with nitrogen plasma activation in the mode of modulated metal fluxes are studied. To compensate for elastic stresses in the structure, the active region was formed in the form of an InN/InGaN superlattice matched over the average lattice parameter with the underlying InGaN buffer layer. It has been shown that during the growth of relatively narrow InN QWs up to 3 nm wide, there is no relaxation of elastic stresses in the active region of the structure, and the dislocation density remains at the level N_D~(3-4)·1010 cm-2, which corresponds to the dislocation density in InGaN-buffer. Such structures demonstrate the most intense PL in the wavelength range of 1.3-1.5 μm. With the growth of wider QWs, the imperfection of the structures sharply increases (N_D&amp;gt;1011 cm-2), which is accompanied by a decrease in the emission intensity. The structures grown with InN/InGaN QWs demonstrated an order of magnitude better temperature stability of PL compared to bulk InN layers (PL quenching by ~3 and ~25 times, respectively, in the temperature range of 77-300 K). Nevertheless, at a low temperature (T=77 K), the PL intensity of the studied structures with InN/InGaN QWs is noticeably inferior to that for the bulk InN layer, which apparently indicates a significant role of nonradiative recombination by the Shockley--Reed--Hall mechanism in structures with QWs (as opposed to Auger recombination in bulk InN). Keywords: indium and gallium nitride, molecular beam epitaxy, quantum well, photoluminescence, dislocations.

Change in structure and luminescent properties of ZnSe and ZnCdSe films irradiated by electron beam

Layers of ZnSe and ZnCdxSe (x ~ 0.32-0.35) grown on GaAs (001) substrates by molecular beam epitaxy method were investigated. The electron beam impact on changes in crystal structure of specimens under examination and on their luminescent properties was studied. Methods of cathode luminescence, transmission electron microscopy, and electron microprobe analysis were applied. It is found that irradiation of specimens in the transmission electron microscope results in stacking faults annealing accompanied by formation of ZnO precipitates with hexagonal crystal structure. Irradiation of specimens in the cathode luminescence plant results in decreased intensity of cathode luminescence layers of ZnSe and ZnCdxSe in question due to radiation-stimulated degradation processes. Key words: point defects, irradiation by electron beam, cathode luminescence, structural changes.