1.3微米发光自组织InAs/GaAs量子点的电致发光研究

用优化的MBE参数生长了1.3μm发光的InAs/GaAs量子点材料,并制成发光二极管,对不同温度和有源区长度下样品的电致发光谱进行了细致的研究.观察到两个明显的电致发光峰,分别对应于量子点基态和激发态的辐射复合发光.实验表明,由于能态填充效应的影响,适当增大量子点发光器件有源区长度,更有利于获得基态的光发射.这个结果提供了一种控制和调节InAs/GaAs量子点发光二极管和激光器的工作波长的方法.     

分子束外延生长的InAs/GaAs自组织量子点发光特性

研究了分子束外延生长的覆盖了1nm的InxAl1-xAs(x=0.2,O.3)和3nm的Ino2Gao8As复合应力缓冲层InAs/GaAs自组织量子点(QD)光致发光(PL)特性.加InAlAs层后PL谱红移到1.33μm,室温下基态和第一激发态间的跃迁能级差增加到86meV.高In组份的InAlAs有利于获得较长波长和较窄的半高宽(FWHM).对于覆盖复合应力缓冲层的QD不会使波长和FWHM发生显著变化,但可以使基态和第一激发态间的能级差进一步增大.这些结果归因于InAlAs能够有效的抑制In的偏析,减少应力,使QD保持较高的高度.同时,由于InAlAs具有较高的限制势垒,可以增加基态和第一激发态间的能级差.     

Self-Organized InAs Quantum Wires on GaAs （331）A Substrates

Self-organized InAs quantum wires (QWRs) were fabricated on the step edges of the GaAs (331)A surface by molecular beam epitaxy. The lateral size of InAs QWRs was saturated by the terrace width (i.e., 9Ohm) while the size along the step lines increased with the increasing thicknesses of the InAs layers, up to 1100nm. The height of InAs QWRs varied from 7.9nm to 13nm. The evolution of the morphology of InAs QWRs was attributed to the diffusion .andsotropy of In adatoms.     

A method to obtain ground state electroluminescence from 1.3μm emitting InAs/GaAs quantum dots grown by molecular beam epitaxy

1.3μm emitting InAs/GaAs quantum dots(QDs) have been grown by molecular beam epitaxy and QD light emitting diodes(LEDs) have been fabricated.In the electroluminescence spectra of QD LEDs,two clear peaks corresponding to the ground state emission and the excited state emission are observed.It was found that the ground state emission could be achieved by increasing the number of QDs contained in the active region because of the state filling effect.This work demonstrates a way to control and tune the emitting wavelength of QD LEDs and lasers.     

Atomic hydrogen induced step bunching and fabrication of quantum wire arrays on GaAs（311） A Substrate by molecular eam epitaxy

Atomic hydrogen assisted molecular beam epitaxy (MBE) is a novel type of epitaxial growth of nanostructures. The GaAs (311)A surface naturally forms one-dimensional step arrays by step bunching along the direction of 〈-233〉 and the space period is around 40nm. The step arrays extend over several μm without displacement. The InGaAs quantum wire arrays are grown on the step arrays as the basis. Our results may prompt further development of more uniform quantum wire and quantum dot arrays.     

1.55μm波长发光的自组织InAs量子点生长

通过引入较长停顿时间,采用分子束外延循环生长方法在350℃低温获得了一种横向聚合的InAs自组织量子点,在荧光光谱中观察到1.55μm波长的发光峰. 通过AFM和PL谱的联合研究,表明此低温循环生长方法有利于在长波长发光的量子点的形成.