Study of Wide Bandwidth All Optical Wavelength Converter using Low Dimensional Quantum Well Structure

自组装量子点（QDs）是由生长材料和衬底之间较大的晶格不匹配引起的，由于其令人着迷的物理性质和在光电子器件中的巨大应用潜力，因此通过Stranski-Krastanov （S-K）生长模式形成的。利用低压金属有机气相外延（MOVPE）技术，研究了在（100）InP衬底上S-K生长模式下InAs量子点（QDs）的生长条件。InAs量子点的生长过程如下：在InP衬底上生长3nm GalnAs缓冲层后，提供TMI和tBA，并在生长中断期间自形成InAs量子点。在实验中，我们得到了InAs点直径与生长温度、压力、供源时间、生长中断时间的关系。量子点密度与生长温度、压力、供源时间和生长中断有很大关系。在生长温度500℃，生长压力15Torr，源供应时间7sec，生长中断时间60sec的条件下，获得了16.7nm的量子点横向尺寸。据我们所知，这个量子点的尺寸是InP衬底上最小的InAs点。我们已经培养出了多堆叠的InAs/InP量子点。单层InAs/InP量子点的PL测量是在低温（10K）下进行的，在1837nm附近的发射峰宽（FWHM）为54.3meV。该波长与计算结果吻合较好。

The optical properties of self-assembled quantum dots (QDs) via Stranski-Krastanov (S-K) growth mode, which is induced by relatively large lattice mismatch between growth material and substrate are currently a subject of intense investigation due to their fascinating physical properties and their strong potential for application in optoelectronics devices.We have shown the growth condition of InAs quantum dots (QDs) on (100)InP substrate under the S-K growth mode by using low pressure metalorganic vapor phase epitaxy (MOVPE). The growth procedure of InAs QDs was as follows. After the growth of 3nm GalnAs buffer layer on the InP substrate, TMI and tBA were supplied and InAs QDs were self-formed during the growth interruption. In the experiment, we obtained the relation between InAs dot diameter and the growth temperature, pressure, and source supplied time, and growth interruption time. The QD density had a greatly dependence on the growth temperature, pressure, and source supplied time and growth interruption. The lateral size of 16.7nm QDs was obtained under a 500 ℃ growth temperature and a 15Torr growth pressure and a 7sec source supplied time and a 60sec growth interruption time. As far as we know this QDs size is the smallest InAs dot on the InP substrate. And we have grown the multi-stacked InAs/InP QDs. The PL measurements of the single-layer InAs/InP QDs were performed at low temperature (10K), and exhibited an emission (FWHM of 54.3meV) around the wavelength of 1837nm. This wavelength was well agreed with the calculation result.