The effect of optical radiation in the visible and near-infrared bands on resistive switching of a MOS stack based on ZrO2(Y) film on an n-Si(001) substrate with self-assembled Ge nanoislands on its surface has been studied. An increase in the resistive switching logical gap was observed upon the photoexcitation, in particular, when the photon energies were smaller than the Si band gap. The effect was associated with the impact of the photovoltage at the Si/Ge/ZrO2(Y) interface. In the latter case, the effect is associated with spatially indirect interband optical transitions in Ge nanoislands.

Методом химического осаждения из газовой фазы, активированной "горячей нитью", выращены гетероэпитаксиальные слои Ge или Ge1-xSnx на высоколегированных донорной примесью (As или Sb) подложках Si(001). Для сравнения такие же слои были выращены на высокоомных подложках Si(001). В тех и других слоях вольт-емкостным методом были измерены профили распределения концентрации носителей заряда по глубине слоев, а в последних слоях дополнительно методом эффекта Холла были измерены подвижности носителей заряда. Установлено, что слои, выращенные на высокоомных подложках, были p-типа проводимости, а слои, выращенные в тех же режимах на высоколегированных подложках, были n-типа с концентрацией электронов в слоях Ge n=(4-9)·1016 см-3, а в слоях GeSn n=(2-4)·1017 cм-3. Экспериментально и теоретически установлено, что эффект автолегирования слоев Ge и GeSn в методе химического осаждения из газовой фазы, активированной "горячей нитью", отсутствует. По нашему мнению, формирование слоев Ge и GeSn n-типа проводимости при выращивании их на высоколегированных донорной примесью (As или Sb) подложках n+-Si(001) связано с сегрегацией этой примеси при росте буфферного слоя Si и с последующим встраиванием ее в растущие слои Ge или GeSn. Ключевые слова: эпитаксия, легирование, Ge, Si, Sn, концентрация.

AIIIBV/Ge/Si (001), AIIIBV/Ge/SOI (001), and AIIIBV/GaAs (001) heterostructures were formed and investigated. The Ge buffer layer was produced by the "hot wire" technique on a Si substrate (001) for the AIIIBV/Ge/Si structure. In the case of the AIIIBV/Ge/SOI, the Ge buffer layer was grown on the SOI (001) substrate by molecular beam epitaxy via two-stage growth. The growth of AIIIBV layers were performed by metalorganic chemical vapor deposition. It is shown that the Ge/SOI formed via two-stage growth allows the growth of AIIIBV layers that are not inferior in structural and optical quality to those formed on the Ge/Si.

Resistive switching effect of separate dislocations in Ag/Ge/Si(001) memristor structures was demonstrated experimentally by Conductive Atomic Force Microscopy. Hysteresis loops typical for bipolar resistive switching were observed in the current-voltage curves of the dislocations due to formation and rapture of Ag filament in the Ge layer as a result of Ag+ ion drift along the dislocation core.

It is shown that two modes of resistive switching – bipolar and volatile unipolar – are peculiar for the Ag/Ge/Si structures with germinating dislocations in the germanium layer. In this modes the structures have stable states of electric current with ION/IOFF ~1.5–2.7. The volatile unipolar type of switching can be caused by the capture of charge carriers to deep levels associated with lattice defects in the Ge film of the memristor. At the same time, bipolar switching is associated with the drift of Ag+ ions along germinating dislocations.

Ge/Si buffer layers grown at different temperatures on Si/SiO2/Si (100) substrates have been fabricated and studied. The Si buffer was grown via molecular beam epitaxy. The Ge layer was produced in a single stage via hot wire chemical vapor deposition process. Structural properties were investigated by high-resolution transmission electron microscopy and reflected high-energy electron diffraction. Such structures can be used in the future as a substrate for growth of high quality light-emitting structures compatible with silicon radiation-resistant integrated circuits. The paper shows the possibility of growth of a single crystal layer of Ge on Si/SiO2/Si (100) through a buffer layer of Si by the hot wire chemical vapor deposition process, and also demonstrates the difficulties that arise in the process of growth of Ge/Si layers on Si/SiO2/Si (100).

AbstractA GaAs/AlAs/GaAs/AlAs/Ge heterostructure grown on a Si/Al_2O_3(1 $$\bar {1}$$ 02) substrate is formed and studied. The Ge buffer layer is produced by the “hot wire” technique, whereas the III–V layers are grown by metal–organic vapor-phase epitaxy. The optical quality of the III–V layers is determined by photoluminescence spectroscopy. Structural studies are performed by high-resolution transmission electron microscopy. The elemental composition is determined by energy-dispersive X-ray spectroscopy. In the study, the possibility of growing a single-crystal GaAs layer on a Si/Al_2O_3 substrate through AlAs/GaAs/AlAs/Ge buffer layers is shown.

AbstractThe photoluminescence spectra of epitaxial n ^+-Ge:P/Si(001) structures are studied. The structures are grown by hot-wire chemical vapor deposition and doped with phosphorus to the maximum electron concentration 1 × 10^20 cm^–3 from a source based on thermally decomposed GaP. The effects of the doping level and rapid thermal annealing of n ^+-Ge:P layers on the photoluminescence spectra are studied. It is demonstrated that the epitaxial n ^+-Ge:P/Si(001) layers grown by hot-wire chemical vapor deposition are promising for application as active regions of light-emitting optoelectronic devices operating in the near-infrared spectral region.

Abstractn ^+-Ge/ p ^+-Si(001) epitaxial structures are grown by hot-wire chemical vapor deposition from GeH_4 at a low substrate temperature (~325°C). Prototype tunnel diodes allowing for monolithic integration into Si-based integrated circuits are formed based on these structures. Doping of the n ^+-Ge layers with a donor impurity (P) to a concentration of >1 × 10^19 cm^–3 is performed via the thermal decomposition of GaP. Distinct regions of the negative differential resistance are observed in the current–voltage characteristics of tunnel diodes.

AbstractA comparative study of the effect of pulsed γ-neutron irradiation on the photosensitivity spectra of Si p – n photodiodes with active layers based on self-assembled GeSi nanoisland arrays and Ge epitaxial layers is performed. The irradiation of photodiodes with GeSi nanoislands is found to not lead to photosensitivity degradation in the spectral region of interband optical absorption in nanoislands (wavelength range of 1.1–1.7 μm). At the same time, a steady decrease in the intrinsic photosensitivity of Si and the photosensitivity of photodiodes based on Ge epitaxial layers with an increase in irradiation dose is observed. This effect is attributed to the accumulation of radiation-induced defects in the Si matrix and deep in Ge epitaxial layers, respectively.

Методом сканирующей ближнепольной оптической микроскопии исследовано пространственное распределение фототока в плоскости p+-n-перехода на базе Si cо встроенными самоформирующимися наноостровками GexSi1-x (x~0.35) при локальном фотовозбуждении зондом микроскопа на длине волны излучения 1310 нм, большей красной границы собственной фоточувствительности Si. На изображениях фототока (картах пространственного распределения фототока в плоскости фотоприемного окна p+-n-фотодиода) обнаружены неоднородности, связанные с межзонным оптическим поглощением в наноостровках GeSi. Результаты работы показывают возможность визуализации индивидуальных наноостровков GeSi на изображениях фототока с пространственным разрешением ~100 нм. DOI: 10.21883/FTP.2017.04.44353.8420

Si/SiGe periodic heterostructures are grown on Si(100) substrates by combined method of heteroepitaxy from the Si atomic flux and GeH 4 molecular flow. The structures have been studied by X-ray diffraction, secondary ion mass spectroscopy and transmission electron microscopy. The data obtained indicate a high structural perfection of the structures, sharp interfaces between the layers, repeatability of thickness and composition of the layers in periodic structures.

Эпитаксиальные слои Si1 - xGex выращены методом молекулярно-лучевой эпитаксии с сублимационным источником кремния и газовым источником германия на подложках кремний-на-сапфире. Выращивание слоев Si1 - xGex непосредственно на подложке сапфира привело к ухудшению структурного совершенства, поэтому в дальнейшем рост осуществляли на буферном слое Si. Методом рентгеновской фотоэлектронной спектроскопии определен профиль распределения элементов Si, Ge и фоновых примесей в слоях. Установлено, что варьирование толщины буферного слоя Si в пределах 50–300 нм не влияет на структуру слоя SiGe. Монокристаллические слои SiGe растут в интервале температур 360–410°C. Изменение концентрации германия в слое в интервале 5–25% не изменяет структуру слоя, но слегка увеличивает шероховатость.

The morphology and PL spectra of self-assembled GeSi/Si(001) nanoislands grown by the hot wire method have been studied for the first time. Nanoisland size and density dependencies on the substrate temperature and the deposited amount of Ge have been found to correspond to those found earlier for the nanoislands grown by MBE. However, the nanoislands tended to coalesce in the whole growth temperature range (500 ÷ 700С). This was related to the presence of GeH4 inside the growth chamber, which enhances the surface diffusion of Ge adatoms and, therefore, promotes the islands coalescence. The PL (77K) spectra show dominant lines related to misfit dislocations in the coalesced islands.

The relations between the parameters of deposition, structure, surface morphology and electrophysical properties of MBE grown thin n-silicon on sapphire films have been established. A transitional layer has been found to form at the initial stages of silicon growth. This layer of thickness up to 0.3 ƒm is a mixture of block oriented crystallites and amorphous phase of silicon. The layer electrical conductivity has a barrier mechanism with an activation energy of 0.1-0.28 eV and small values of mobility 30-60 cm2/Vs. The dependence of formation of deep acceptors in silicon on layer thickness has been discovered.