奈米金顆粒於電漿活化矽基板對氮化鎵奈米線成長之研究

Synthesize of GaN Nanowires Using Gold Nanoparticles on Plasma-Activated Silicon Substrate

羅佩嵐(P.L. LO) ； 李國豪(K.H. Lee) ； 陳引幹(I.G. Chen)

《鑛冶：中國鑛冶工程學會會刊》 53卷1期 (2009/03) Pp. 89-99

https://doi.org/10.30069/MM.200903_53(1).0008

摘要

本實驗使用奈米金當催化劑，用化學氣相沈積法（CVD）的方式，透過氣相－液相－固相成長機制（VLS growth mechanism）在矽基板上成功地成長出小線徑的氮化鎵奈米線。首先以電漿系統活化矽基板表面後，再將矽基板浸泡於以烯基硫醇（CH_2=CH(CH_2)_nSH）為保護劑的奈米金溶液中，達到奈米金鍵結於矽基板上的目的。由X-射線光電子光譜（XPS）分析結果可知，電漿處理確實可達成矽基板與奈米金形成共價鍵結（Si-C鍵）。在掃描式電子顯微鏡（SEM）的觀察結果顯示，奈米金粒徑與氮化鎵奈米線線徑的尺寸相近。奈米金粒徑愈小，奈米線愈長（粒徑小至約25nm時，長度可達1um以上），即催化能力愈佳。在室溫光激發螢光光譜（PL）實驗結果顯示，隨奈米線線徑縮小（125nm→31nm），PL峰值位置有藍位移的現象（364nm→ 357nm）。而能隙偏移量與線徑倒數成線性關係變化，此原因與奈米線的表面再結合效應有關。在低溫（80K）PL量測中，亦發現隨線徑縮小，藍移的現象（357nm→353nm）。而當PL量測溫度從300K降低到80K時，峰值位置有藍移現象，意即溫度降低時，氮化鎵能隙會變大，符合Varshini equation的描述。當奈米線線徑縮小至31nm時，PL光譜中有一次要峰值產生，落在380～390nm。產生此訊號的來源，可能原因為：（1）烏采結構（Wurtzite）奈米線內含少量的立方體（cubic）結構氮化鎵生成（2）氮化鎵施體－授體對（donor-acceptor pair，簡稱為DAP）訊號。（3）烏采結構（Wurtzite）奈米線內含有少量的氧化鎵。

關鍵字

氮化鎵奈米線 ； 奈米金 ； 電漿

並列摘要

In this research, we successfully applied the vapor- liquid-solid (VLS) growth mechanism and catalytic gold nanoparticles (Au NPs) to produce tiny diameter gallium nitride nanowires (GaN NWs) on plasma-treated silicon(Si) substrate. The Si substrates were activated by plasma processing and followed by immersing in alkene-1-thiol-protected Au NPs solutions. The X-ray photoelectron spectroscopy(XPS) analysis results showed that plasma treatment was useful to activate Si surface to form Si-C bond. The observations of scanning electron microscope (SEM) revealed that the size of NPs and the diameter of NWs were identical. It was shown that the smaller size of NPs corresponded to better catalysis ability. For different sizes of NWs, the photoluminescence (PL) measurements indicated a blue shift of emission peaks in 300K and 80K, respectively. In 300K, the shift of bandgap energy was inversely proportional to the diameter of NWs, which was attributed to the surface recombination effect of NWs. The change of emission peaks in 300K and 80K can be correlated by Varshini's equation. When the diameter was 31nm, the PL spectra showed an abnormal signal between 380-390nm. The abnormal signal may be induced by (1) generation of GaN cubic structure, (2) donor-acceptor-pair (DAP) emission and (3) generation of Ga_2O_3 structure.

並列關鍵字

G GaN nanowires ； Gold nanoparticles ； plasma