The growth of high-quality substrates for microelectronic applications is one of the key elements that could lead society towards a more sustainable green economy. Today, silicon plays a central role in the semiconductor device (including power) industry: silicon wafers of high-purity (99.0% or higher) single-crystalline material can be obtained by a sequence of growth methods starting from the liquid phase and by subsequent epitaxy. Due to the absence of a stable liquid phase, this combination of processes cannot be used for the growth of the emerging material for power electronics: silicon carbide (SiC).
Today, an international team of researchers led by Antonino La Magna and Giuseppe Fisicaro from the Institute for microelectronics and microsystems (Cnr-Imm) of the National Research Council of Italy (Catania) has demonstrated through a theoretical and experimental study ways of "controlling" the crystal imperfections inside cubic silicon carbide or 3C-SiC. Among the various structures of SiC (called polytypes), 3C-SiC is at the same time the most similar to silicon and the most promising for a series of applications. The study is published in the journal Applied Physics Reviews and has been selected by the editorial board as a "featured article": it describes the atomic mechanisms that regulate the kinetics of extended defects that are, in this material, planes of atoms in incorrect positions with respect to those occupied in the ideal crystal. The research, performed in the framework of the H2020 European project CHALLENGE, aims at controlling the crystalline imperfections within 3C-SiC for applications in power devices based on prohibited broadband materials, potentially revolutionizing the field of microelectronics.
Researchers have identified the atomistic mechanisms responsible for the generation and evolution of extended defects.In particular, it has been shown that anti-phase defects – i.e. planar crystallographic defects that represent the contact boundary between two crystal regions with switched bonds (C-Si instead of Si-C) - are a critical source of other extended defects in variousconfigurations.The possible reduction of these anti-phase defects is particularly important to obtain good-quality crystals that can be used in electronic devices and allow their large-scale production.
The study exploited innovative simulations obtained through a computational code (MulSKIPS, www.github.com/giuseppefisicaro/mulskips) which is able to realistically describe the complex kinetics of tens of billions of atoms over very long times (minutes or hours).The code helped to shed light on the various mechanisms of interaction between the different types of extended defects and their impact on the electronic properties of this material.
Antonino La Magna
CNR - Istituto per la microelettronica e microsistemi
Zona Industriale VIII Strada 5