IV族碳化矽與矽鍺碳化合物半導體非線性光學

Abstract

將C-C和C=C鍵的共軛鏈嵌入碳化矽(SiC)基質中，因大量的π電子促進光學非線性增強。以PECVD生長技術製程C/Si組成比從0.98到1.12的的含有類金剛石C-C和類石墨的C=C鍵的富碳碳化矽。增加的C/Si組成比不僅將SiC能寬從2.3eV擴展到2.5eV，而且由於間隙碳共軛鏈的吸收而引起拖尾基峰，擴大了非線性吸收係數。合成的SiC薄膜的β’隨C/Si比的增加從702到2621cm/GW。這些伴隨著類石墨的C=C鍵且具有短鍵長和較小有效質量的離域π電子，大大提高了SiC的非線性折射率，從4.65×10-11到6.23×10-11cm2/W。對不同組成比例的Si1-x-yGexCy材料的生長機理和光學非線性進行了論證和討論。隨著較高的C和較低的Ge，生長機制是F-M模式的增長。富Ge元素促進SiC複合物的合成，並由SK模式生長而生成島狀表面。在島結構的底部的非均質成長的核為FCC晶體結構的C。此外，可以在島結構的頂部觀察到Si1-x-yGexCy的FCC結構。調整Si-Si，Ge-Ge和C=C的組成比例，有可能將Si1-x-yGexCy的非線性折射率擴大到10x-11cm2/W。通過植入大量C=C鍵使Si1-x-yGexCy形成富碳結構，有助於表現出更大的n2值，以促進克爾效應，從而增強非線性光學開關應用。

By embedding the C-C and C=C bond related conjugated chains into the silicon carbide (SiC) matrix, the enriched π-electrons can be realized to facilitate the optical nonlinearity enhancement. The C-rich SiC with different concentrations of buried diamond-like C-C and graphite-like C=C bonds as synthesized by varying the C/Si composition ratio from 0.98 to 1.12 during PECVD growth. The increased C/Si composition ratio not only extends the SiC band edge from 2.3 eV to 2.5 eV, but also induces trailing pedestal peaks due to the absorption of the interstitial carbon conjugated chains which enlarges the nonlinear absorption coefficient of the synthesized SiC film from 702 to 2621 cm/GW. These delocalized π-electrons with short displacement and small effective mass accompanied with graphite-like C=C bond greatly enhances the nonlinear refractive index of the SiC from 4.65×10-11 to 6.23×10-11 cm2/W.The growth mechanism and optical nonlinearity of the Si1-x-yGexCy material synthesized with different s are demonstrated and discussed. With higher C and under low Ge, the growth mechanism is the F-K mode growth. The enrich Ge facilitates the synthesis of aforementioned SiC composites to form the islands-like surface caused by SK-mode growth. The heterogeneous C nucleus exhibits the FCC crystalline structure in the bottom of the island structure. The FCC structures of Si1-x-yGexCy can be observed on the top of island structure. Designing the Si1-x-yGexCy with the Si-Si, Ge-Ge, and C=C enlarge its nonlinear refractive index to 10x-11 cm2/W. By detuning the C-rich Si1-x-yGexCy with plenty of C=C bonds, the Si1-x-yGexCy exhibits larger n2 value to facilitate the Kerr effect for enhancing the nonlinear optical switching applications.