Molecular Beam Epitaxy of Layered Group III Metal Chalcogenides on GaAs(001) Substrates

Abstract

Development of molecular beam epitaxy (MBE) of two-dimensional (2D) layered materials is an inevitable step in realizing novel devices based on 2D materials and heterostructures. However, due to existence of numerous polytypes and occurrence of additional phases, the synthesis of 2D films remains a difficult task. This paper reports on MBE growth of GaSe, InSe, and GaTe layers and related heterostructures on GaAs(001) substrates by using a Se valve cracking cell and group III metal effusion cells. The sophisticated self-consistent analysis of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy data was used to establish the correlation between growth conditions, formed polytypes and additional phases, surface morphology and crystalline structure of the III–VI 2D layers. The photoluminescence and Raman spectra of the grown films are discussed in detail to confirm or correct the structural findings. The requirement of a high growth temperature for the fabrication of optically active 2D layers was confirmed for all materials. However, this also facilitated the strong diffusion of group III metals in III–VI and III–VI/II–VI heterostructures. In particular, the strong In diffusion into the underlying ZnSe layers was observed in ZnSe/InSe/ZnSe quantum well structures, and the Ga diffusion into the top InSe layer grown at ~450 °C was confirmed by the Raman data in the InSe/GaSe heterostructures. The results on fabrication of the GaSe/GaTe quantum well structures are presented as well, although the choice of optimum growth temperatures to make them optically active is still a challenge.

Исследование ван-дер-ваальсовых кристаллов GaSe и GaS-=SUB=-x-=/SUB=-Se-=SUB=-1-x-=/SUB=- методом фотоотражения

“…Использованный в данной работе метод фотоотражения (ФО) является разновидностью модуляционной оптической спектроскопии [18], позволяющей бесконтактно определять напряженность электрического поля и положение уровня Ферми в приповерхностной области полупроводниковых кристаллов [23,24], концентрацию свободных носителей заряда [25] и т. д. Также спектроскопия фотоотражения может быть использована для оценки степени взаимодействия эпитаксиальных слоев графеноподобных кристаллов с подложкой [26] при их выращивании методом молекулярно-пучковой эпитаксии [27].…”

Personalized energy systems based on nanostructured materials

“…At the same time, the actual achieved efficiency of solar cells, which has significantly increased from 11 to 15 % for those previously created on the basis of silicon and germanium, currently does not exceed 39 -41 %, even for a new generation of photovoltaic semiconductor converters. They are developed on the basis of multilayer, for example, AlInGaPAs/GaAs/Si, InGaP, InGaAs and Ge nanoheterostructures of cascade type grown by gas-phase epitaxy from organometallic compounds on silicon and germanium substrates [98][99][100][101][102][103][104][105][106]. At the same time, an increase in the maximum power of the solar cells is achieved not only by improving the structure of p-n junctions, but also by focusing the sun's rays using mirrors and Fresnel mini-lenses.…”

Инфракрасное Фотоотражение Полупроводниковых Материалов a-=sup=-3-=/Sup=-B-=sup=-5-=/Sup=- ( О Б З О Р )

“…В заключение подраздела, посвященного ФО GaAs, отметим, что этот полупроводник был и остается одной из наиболее подходящих подложек для эпитаксии новых материалов (в силу своей доступности, технологичности и прочности). В качестве примера таких материалов можно привести двумерные графеноподобные полупроводники и, в частности [46], халькогениды металлов третьей группы таблицы Д.И. Менделеева.…”