奈米矽晶微碟共振腔發光特性與迴音廊模態之研究

Abstract

我們以電漿增強式化學氣相沈積法成長並在高溫熱退火下形成奈米矽晶的薄膜當作主動層，成功製作出了內含奈米矽晶的微碟共振腔，在室溫環境下，在600nm~1000nm的波段之中，量測到明顯的迴音廊模態。 奈米矽晶微碟共振腔分別以兩種不同的微影方式製作，以標準微影製程做出直徑10μm與20μm的微碟，以電子束微影製程做出直徑4、6、8、10μm的微碟，量測直徑8μm的微碟，Q值最高可達到1200，而直徑10μm的微碟可達到2400，我們同時也製作了厚度較厚的直徑10μm的微碟，希望能夠增加在主動層內的侷限。我們也能利用奈米矽晶/二氧化矽超晶格結構製作出微碟共振腔，同時也量測到了迴音廊模態。 最後針對入射功率的改變，量測輸出功率的變化，但沒有觀察到雷射閥值，主要原因為在很低的功率下，奈米矽晶就已經達到飽和狀態，而入射功率與線寬的關係部分應是有受激載子吸收的效應，造成模態擴張線寬增加的趨勢。

We have successfully fabricated optically active microdisk resonators with Si nanocrystals grown by plasma enhanced chemical vapor deposition (PECVD) and the post-annealing process. The room-temperature photoluminescence from single microdisk shows the characteristic modal structure of whispering-gallery modes in the wavelength between 600nm and1000nm. We fabricated Si-nanocrystal-embedded microdisk resonators by two different lithography processes. We use standard lithography to fabricate the microdisk resonators with diameters of 10μm and 20μm and electron-beam lithography for 4-μm, 6-μm, 8-μm and 10-μm-diameter disks. The quality factors of 8μm and 10μm disks can reach 1200 and 2400 respectively. We also fabricated thicker 10-μm-diameter disks to increase the confinement of the disk. We can also use Si-nc/SiO2 superlattice as the active layer in the microdisk resonators and the WGMs were observed clearly Finally, we discussed the relation between pump power and output power. We observed the saturation of the excitable nanocrystals at low pump power and the linewidth broadening with pump power increasing due to the excited carrier absorption (ECA).