Crystalline-Phase Switching in Heterostructured Ga(As,P) Nanowires under the Impact of Elastic Strains
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INTERNATIONAL SYMPOSIUM “NANOPHYSICS AND NANOELECTRONICS”, NIZHNY NOVGOROD, MARCH 10–13, 2020
Crystalline-Phase Switching in Heterostructured Ga(As,P) Nanowires under the Impact of Elastic Strains N. V. Sibireva,*, Yu. S. Berdnikovb, and V. N. Sibirevc a ITMO
University, St. Petersburg, 197101 Russia Petersburg State University, St. Petersburg, 198504 Russia c St. Petersburg Mining University, St. Petersburg, 199106 Russia *e-mail: [email protected] b St.
Received April 15, 2020; revised April 21, 2020; accepted April 21, 2020
Abstract—The effect of elastic stresses on the Ga(As, P) crystalline phase of nanowires is studied. It is shown that the elastic stresses can lead to the stable growth of whisker nanocrystals in the metastable phase. The possibility of crystal-phase switching inside a GaP nanowire after the appearance of a Ga(As, P) insert is described. Keywords: crystalline nanowires, polytypism, gallium phosphide, wurtzite DOI: 10.1134/S1063782620100267
1. INTRODUCTION The Ga(As, P) crystalline phase continues to be one of the most actively used III–V semiconductors for optoelectronic applications [1–4]. For Ga(As, P) applications, the key factors are a small mismatch between the GaP and silicon lattices (less than 1%) [3–5] and the presence of a direct band gap at phosphorus concentrations less than 45% [5]. Together, it makes possible the formation of defect-free planar Ga(As, P) heterostructures on silicon and, on their basis, optoelectronic devices of the red and yellow ranges [1–3]. The mismatch between the GaAs and GaP lattices is also not large, less than 4% [3, 5]. Nevertheless, even such an insignificant mismatch of the lattices requires the creation of metamorphic buffer layers for relieving elastic stresses between the silicon substrate and the active zone of an optoelectronic device. In this case, the formation of atomically smooth GaAs/GaP heterojunctions is possible in crystalline nanowires (NWs) [6]. A large area of the lateral surface, which allows the efficient removal of elastic stresses at the heterointerface [7], facilitates the fabrication of axial heterostructures in III–V NWs. The most common method for the synthesis of III–V NWs is vapor–liquid–crystal growth. In such processes, the formation of abrupt heterojunctions is limited by the solubility of elements in the catalyst drop [8, 9]. And here Ga(As, P) has proved to be a very convenient material. This is explained by the fact that arsenic and phosphorus are poorly soluble in most of the catalysts
under use for the growth of III–V NWs [10]. Therefore, the first axial heterostructures with an atomically smooth interface were demonstrated exactly for GaAs/GaP [6] and InAs/InP nanowires [11]. Almost immediately, it was found that thin GaAs and GaP NWs grow in the crystalline phase of wurtzite, while the sphalerite phase is thermodynamically stable under normal conditions [6, 12–14]. In this case, GaP in the stable cubic phase (sphalerite) is an indirect-gap semiconductor, and it is a direct-gap semiconductor in the metastable h
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