Chemical Vapor Growth of Silicon Phosphide Nanostructures
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.437
Chemical Vapor Growth of Silicon Phosphide Nanostructures Zhuoqun Wen#, Yiping Wang#, Zhizhong Chen, Jian Shi*
Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180
#
equally contributed correspondence: [email protected]
*
ABSTRACT
In the search for chemically stable two-dimensional (2D) materials with high in-plane mobility, proper bandgap, and compatibility with vapor-based fabrication, van der Waals semiconductor SiP has become a potential candidate as a robust variation of black phosphorous. While bulk SiP crystals were synthesized in the 1970s, the vapor-based synthesis of SiP nanostructures or thin films is still absent. We here report the first chemical vapor growth of SiP nanostructures on SiO2/Si substrate. SiP islands with lateral size up to 20 μm and showing well-defined Raman signals were grown on SiO2/Si substrate or on SiPcontaining concentric rings. The presence of SiP phase is confirmed by XRD. The formation of rings and islands is explained by a multiple coffee ring growth model where a dynamic fluctuation of droplet growth front induces the topography of concentric ring surfaces. This new growth method might shed light on the controlled growth of group IV-III high-mobility 2D semiconductors.
INTRODUCTION Two dimensional (2D) materials with high in-plane charge carrier mobility, proper bandgap, sufficient chemical stability, and compatibility with vapor-based fabrication methods are highly desired in the semiconductor community. Graphene has high room-temperature mobility > 10000 cm2/V•s but zero bandgap [1]. Transition metal dichalcogenides (TMDCs) have bandgap 1.0 eV~1.9 eV while carrier mobility is
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typically below 200 cm2/V•s due to the presence of transition metals [2, 3]. Among 2D semiconductors composed of main-group elements, black phosphorus (BP) has ideal room-temperature mobility ~400 cm2/V•s and bandgap ~2 eV [4]. However, BP family is vulnerable under ambient environment [5]. Although BP and its derivatives can be stabilized by alloying with group V elements without compromising mobility and bandgap much, e.g. AsP [5], their vapor-based synthesis has so far remained challenging. Inspired by the alloying of BP, 2D van der Waals (vdW) semiconductor SiP, a chemically-stabilized variant of BP, re-evoked the attention of semiconductor research in recent years [6]. As shown in figure 1(a), the room temperature phase of SiP has an orthorhombic structure with space group Cmc21 [7]. Each layer is composed of wurtzitelike interconnected tetrahedral sites that compose both Si-P and Si-Si bonds. Between neighbouring layers, a vdW gap ~2.9 Å is opened between bonded P atoms to sustain local charge neutrality. Qualitatively, the decent electro
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