Indium selenide (In₂Se₃) has got much recent attraction in a variety of research areas mainly due to its multiphase structure. Many existing studies, however, have focused on growth of α and β phase, while chemical vapor deposition (CVD) growth of the γ-phase has only been achieved for micon-thick flakes with the assistance of iodine trichloride (ICl₃) catalysts. Here, we present the “catalyst-free” CVD growth of β and γ phase In₂Se₃ flakes with thicknesses down to only a few nanometers. The structural, optical and ferroelectric properties of the grown samples were investigated carefully by using various techniques. Optical microscope and Raman spectroscopy studies revealed that triangular and hexagonal shaped β and γ phases were grown at different substrate temperatures, respectively. The second-harmonic generation (SHG) measurement confirmed that β has centrosymmetric structure and γ phase has non-centrosymmetric structure. The ferroelectric properties of the γ-In₂Se₃ were measured along in-plane (IP) and out-of-plane (OOP) directions, for the first time, by employing piezo-force microscope (PFM). The non-monotonic thickness dependence of the ferroelectricity was found and explained with the combination of Raman and SHG measurements. The catalyst-free growth of γ-In₂Se₃ and the observation of ferroelectricity in it would be a valuable addition in the field of ferroelectric and piezoelectric switching devices.

硒化铟（In ₂ Se ₃）由于其多相结构而在许多研究领域中引起了越来越多的关注。然而，许多现有的研究集中在α和β相的生长上，而只有在三氯化碘（ICl ₃）催化剂的辅助下，超粘稠薄片才实现了γ相的化学气相沉积（CVD）生长。在这里，我们介绍了在₂ Se ₃中β和γ相的“无催化剂” CVD生长厚度仅为几纳米的薄片。通过使用各种技术仔细研究了生长样品的结构，光学和铁电性能。光学显微镜和拉曼光谱研究表明，三角形和六边形的β和γ相分别在不同的底物温度下生长。二次谐波（SHG）测量结果证实，β具有中心对称结构，γ相具有非中心对称结构。所述的铁电性γ-在₂硒₃首次使用压电显微镜（PFM）沿平面（IP）和平面外（OOP）方向进行了测量。结合拉曼和SHG测量发现并解释了铁电的非单调厚度依赖性。的不含催化剂的生长γ-在₂硒₃和铁电性在它的观察将在铁电和压电开关装置的领域的重要补充。