Goktas Nebile Isik, Dubrovskii Vladimir G, LaPierre Ray R
Department of Engineering Physics, McMaster University, Hamilton, ON L8S 4L7, Canada.
Department of Physics, St. Petersburg State University, Universitetskaya Emb. 13B, 199034 St. Petersburg, Russia.
J Phys Chem Lett. 2021 Feb 4;12(4):1275-1283. doi: 10.1021/acs.jpclett.0c03712. Epub 2021 Jan 26.
GaAs-InGaAs-GaAs core-shell-shell nanowire (NW) structures were grown by gas source molecular beam epitaxy using the selective-area, self-assisted, vapor-liquid-solid method. The structural, morphological, and optical properties of the NWs were examined for different growth conditions of the InGaAs shell. With increasing In concentration of the InGaAs shell, the growth transitioned from preferential deposition at the NW base to the Stranski-Krastanov growth mode where InGaAs islands formed along the NW length. This trend is explained within a nucleation model where there is a critical In flux below which the conformal growth is suppressed and the shell forms only at the NW base. Low growth temperature produced a more uniform In distribution along the NW length but resulted in quenching of the photoluminescence (PL) emission. Alternatively, reducing the shell thickness and increasing the V/III flux ratio resulted in conformal InGaAs shell growth and quantum dot-like PL emission. Our results indicate a pathway toward the conditions for conformal InGaAs shell growth required for satisfactory optoelectronic performance.
采用选择性区域、自辅助气-液-固方法，通过气体源分子束外延生长了GaAs-InGaAs-GaAs核-壳-壳纳米线（NW）结构。针对InGaAs壳层的不同生长条件，研究了纳米线的结构、形态和光学性质。随着InGaAs壳层中In浓度的增加，生长模式从优先在纳米线基部沉积转变为Stranski-Krastanov生长模式，即沿纳米线长度形成InGaAs岛。这种趋势在成核模型中得到了解释，在该模型中存在一个临界In通量，低于该通量时，共形生长受到抑制，壳层仅在纳米线基部形成。低生长温度使In沿纳米线长度分布更均匀，但导致光致发光（PL）发射猝灭。相反，减小壳层厚度并增加V/III通量比导致共形InGaAs壳层生长和量子点状PL发射。我们的结果表明了一条通往实现令人满意的光电性能所需的共形InGaAs壳层生长条件的途径。
