Control of local surface strain by using EB process

通过控制化学束外延中砷/磷的供给，研究了自组织InGaAs点的原位成分变化。由于砷/磷原子在点周围的磷/砷的替代，表面结构的变化从InGaAs点的InGaAsP平坦表面，反之亦然，根据砷/磷曝光。点结构和平坦表面之间的过渡表面被亚稳定化，并观察非原位以找出点形成过程。结果发现，在点形成过程中，发育良好的点的密度（而不是致密点的尺寸）正在增加。提出了两种用砷/磷置换技术原位改变量子点结构的新方法。对于InAs点重组，较小的InAs点消失，而形成较大的InAs点。在用脉冲AsH_3曝光分步网点再形成时附加铟或镓的检查中，只有在加铟的情况下，网点才因过度应变而聚结。用氟的电子回旋等离子体辐照GaAs或InP制备了氟化镓或氟化铟薄膜。氟化物薄膜具有电子束敏感性，在电子束辐照下发生分解反应。

In situ composition change of self-organized InGaAs dots has been investigated by means of the control of arsenic/phosphorus supply in chemical beam epitaxy. Due to the replacement of arsenic/phosphorus atoms in the dots by ambient phosphorus/arsenic, surface structure changes from the InGaAs dots to an InGaAsP flat surface and vice versa according to the arsenic/phosphorus exposure. Transitional surfaces between the dot structure and a flat surface were metastabilized and observed ex situ to figure out the dot formation process. It was found that the density of well-developed dots (not the size of dense dots) was increasing during the dot formation. Two new approaches to modifying the dot strucure in situ by using the arsenic/phosphorus replacement technique were demonstrated. For InAs dot reformation, smaller InAs dots disappeared and larger InAs dots were formed instead. In the examination of additional suppy of indium or gallium during step-by-step dot reformation with pulse AsH_3 exposure, the coalescence of dots occurred due to excess strain only in the case of indium addition. Thin films of gallium flouride or indium flouride were fabricated by exposuring GaAs or InP to electron cyclotron plasma of flourine. The flouride films were found to be electron beam (EB) sensetive, that the decomposition reaction occurs by EB irradiation.