Recent Progress In Epitaxial Growth Research Articles

A Review of Recent Progress in β‐Ga2O3 Epitaxial Growth: Effect of Substrate Orientation and Precursors in Metal–Organic Chemical Vapor Deposition

Gallium oxide (Ga2O3) is a highly promising ultrawide‐bandgap semiconductor for power electronics that emerged about a decade ago. Epitaxial growth Ga2O3 at the small scale is demonstrated. In order to develop scalable manufacturing of high‐performance epitaxial structures, in‐depth understanding of the fundamental growth processes, control parameters, and mechanism is imperative. This review discusses the recent progress in epitaxial growth of β‐Ga2O3 films and highlights challenges in obtaining high growth rate, low defects, and high carrier mobilities. Compared with the other epitaxy methods, metal–organic chemical vapor deposition (MOCVD) offers a wider growth window and precursor selection option, to minimize the tradeoff between crystal quality and growth rate. Growth rate is inversely proportional to temperature, within a certain temperature window, because of the unavoidable premature gas‐phase reactions and desorption of the highly volatile gallium suboxide (Ga2O) at elevated temperatures. Growth defects, background impurity incorporation, and carrier mobilities can be affected by the choice of MOCVD precursors, nucleation, and adsorption/desorption/diffusion of adatoms on substrate surfaces of different orientations, including the effect of growing on cleavage and noncleavage planes. This review summarizes the current status of the epitaxial growth of β‐Ga2O3 and analyzes the major factors that enhance mobility and reduce background doping concentration. The insights gained help advance the manufacturability of device‐grade epitaxial thin films.

Recent progress in epitaxial growth of two‐dimensional phosphorus

AbstractPhosphorus is an important non‐metal element with many allotropes and tunable electronic properties. As one of the most important allotropes of phosphorus, two‐dimensional (2D) black phosphorus (BP) possesses many extraordinary properties, such as high charge carrier mobility with high on/off ratio, thickness‐dependent direct bandgap varying from 0.3 to 2 eV, and anisotropic electrical, optical and thermal properties. Inspiring by the success of 2D BP, other 2D phosphorus allotropes with intriguing properties for next‐generation electronic and optoelectronic devices have also attracted much attention. However, large‐scale growth of high‐quality 2D single/few‐layer phosphorus remains a great challenge. In this review, we highlight recent progress achieved on 2D phosphorus, with special focus on the epitaxial growth of 2D BP films, blue phosphorus (BlueP) monolayers as well as phosphorus‐metal porous networks. The remaining challenges and future perspectives on the development of monolayer phosphorus or phosphorus‐metal alloys are also provided.

Recent progress in epitaxial growth of III–V quantum-dot lasers on silicon substrate

In the past few decades, numerous high-performance silicon (Si) photonic devices have been demonstrated. Si, as a photonic platform, has received renewed interest in recent years. Efficient Si-based III–V quantum-dot (QDs) lasers have long been a goal for semiconductor scientists because of the incomparable optical properties of III–V compounds. Although the material dissimilarity between III–V material and Si hindered the development of monolithic integrations for over 30 years, considerable breakthroughs happened in the 2000s. In this paper, we review recent progress in the epitaxial growth of various III–V QD lasers on both offcut Si substrate and on-axis Si (001) substrate. In addition, the fundamental challenges in monolithic growth will be explained together with the superior characteristics of QDs.

Weyl nodes in periodic structures of superconductors and spin-active materials.

Motivated by recent progress in epitaxial growth of proximity structures of s-wave superconductors (S) and spin-active materials (M), in this paper we show that certain periodic structures of S and M can behave effectively as superconductors with pairs of point nodes, near which the low-energy excitations are Weyl fermions. A simple model, where M is described by a Kronig-Penney potential with both spin-orbit coupling and exchange field, is proposed and solved to obtain the phase diagram of the nodal structure, the spin texture of the Weyl fermions, as well as the zero-energy surface states in the form of open Fermi lines (Fermi arcs). As a second example, a lattice model with alternating layers of S and magnetic Z2 topological insulators is solved. The calculated spectrum confirms previous predictions of Weyl nodes based on the tunnelling Hamiltonian of Dirac electrons. Our results provide further evidence that periodic structures of S and M are well suited for engineering gapless topological superconductors.This article is part of the theme issue 'Andreev bound states'.

Epitaxial Growth of III-V Nanowires on Group IV Substrates

ABSTRACTSemiconducting nanowires are emerging as a route to combine heavily mismatched materials. The high level of control on wire dimensions and chemical composition makes them promising materials to be integrated in future silicon technologies as well as to be the active element in optoelectronic devices.In this article, we review the recent progress in epitaxial growth of nanowires on non-corresponding substrates. We highlight the advantage of using small dimensions to facilitate accommodation of the lattice strain at the surface of the structures. More specifically, we will focus on the growth of III–V nanowires on group IV substrates. This approach enables the integration of high-performance III–V semiconductors monolithically into mature silicon technology, since fundamental issues of III–V integration on Si such as lattice and thermal expansion mismatch can be overcome. Moreover, as there will only be one nucleation site per crystallite, the system will not suffer from antiphase boundaries.Issues that affect the electronic properties of the heterojunction, such as the crystallographic quality and diffusion of elements across the heterointerface will be discussed. Finally, we address potential applications of vertical III–V nanowires grown on silicon.

Epitaxial Growth of III-V Nanowires on Group IV Substrates

AbstractSemiconducting nanowires are emerging as a route to combine heavily mismatched materials. The high level of control on wire dimensions and chemical composition makes them promising materials to be integrated in future silicon technologies as well as to be the active element in optoelectronic devices.This ar ticle reviews the recent progress in epitaxial growth of nanowires on non-corresponding substrates. We highlight the advantage of using small dimensions to facilitate accommodation of the lattice strain at the surface of the structures. More specifically, we will focus on the growth of III-V nanowires on Group IV substrates. This approach enables the integration of high-perform ance III-V semiconductors monolithically into mature silicon technology, since fundamental issues of III-V integration on Si such as lattice and thermal expansion mismatch can be overcome. Moreover, as there will only be one nucleation site per crystallite, the system will not suffer from antiphase boundaries.Issues that affect the electronic properties of the heterojunction, such as the crystallographic quality and diffusion of elements across the heterointerface, will be discussed. Finally, we address potential applications of vertical III-V nanowires grown on silicon.

Recent progress in epitaxial growth: GaAs, a-GaAs:H and a-Al xGa 1−xAs:H prepared by thermal and flash evaporation

In recent technology exciting advances have been made in developing new alloys to comply with the requirements of research and development. One of the most promising materials is GaAs alloys. In this paper, a review of recent advances in preparing stoichiometric single-crystal GaAs and its amorphous alloys by thermal and flash evaporation is presented. The resulting materials showed better composition, electrical and optical properties as compared with published data.

Progress in epitaxial growth of SiC

Recent progress in epitaxial growth of SiC in the author's group is surveyed. Growth of 3C-SiC on a Si substrate, a typical success in heteroepitaxial growth with large lattice mismatch, is briefly reviewed. Step-controlled epitaxy of 6H-SiC, which the author's group named and which is a key technology for future development, is discussed in detail. The growth mechanism and effects of off-direction and off-angle are described. An electrostatic model for explaining polytype inheritance in SiC is proposed. As an advanced epitaxial growth, atomic layer epitaxy in SiC crystal growth by gas source molecular beam epitaxy is given.