采用低压金属有机物化学气相沉积(LP-MOCVD)技术在GaAs(001)衬底上制备GaSb量子点, 研究了反应室压强对改善GaSb/GaAs量子点形貌各向异性的影响。通过Sb表面处理方法, 在GaAs衬底上形成低表面能的Sb-Sb浮层, 实现以界面失配(IMF)生长模式对GaSb量子点诱导生长。用原子力显微镜(AFM)对各样品的量子点形貌进行了表征, 结果表明GaSb量子点形貌各向异性明显且沿［110］方向拉长。在压强条件为10 kPa时, IMF生长模式导致不对称岛的长宽比大于3, 由于低能量(111)侧面的存在, GaSb量子点优先沿［110］方向生长而不是与之垂直的［110］方向。压强降低至4 kPa时量子点密度增大为8.3×109 cm-2, 量子点形貌转变为对称的半球形且长宽比约为1。低的压强降低了吸附原子的扩散激活能从而增大了扩散长度, 可以有效改善GaSb量子点的各向异性。

GaSb quantum dots were directly grown on (001) GaAs substrates by metal organic chemical vapor deposition. The effect of reaction chamber pressure on the size anisotropy of GaSb/GaAs quantum dots was analyzed. By the Sb surface treatment, a floating layer of Sb-Sb with low surface energy is formed on a GaAs substrate to achieve growth of GaSb quantum dots with an interfical misfit(IMF) growth mode. The morphologies of GaSb quantum dots were characterized by atomic force microscopy (AFM), and the results showed that the anisotropy of GaSb quantum dots is significant and elongated along the ［110］ direction. With the reaction pressure of 10 kPa, the aspect ratio of the asymmetric island caused by IMF growth mode is more than 3. Because of the low energy for (111) sidewalls, the GaSb quantum dots preferentially grow up along the ［110］ direction rather than the ［110］ direction. When eaction pressure is reduced to 4 kPa, the density of quantum dots increases to 8.3×109 cm-2. The shape of the quantum dots transforms into a symmetrical hemisphere and the aspect ratio is approximately 1. Because the low pressure reduces the activation energy of the atoms and increases the diffusion length, the anisotropy of GaSb quantum dots can be effectively improved.