以垂直布氏長晶法生長CsGeI3晶體及其性質研究

Abstract

本研究是以熱反應法加上布氏長晶法成長CsGeI3晶體，成功的合成複晶原料，並以無晶種方式利用幾何淘汰原理成長晶體，接著以先前較佳的晶體作為晶種定向生長單晶，而能獲得沿著（200）面生長的晶體。 我們將所成長之晶體做了變溫及不同聚焦情況之PL量測，結果發現晶體會因雷射聚焦程度不同而產生相變情形，螢光峰會由低溫相（R3m）的409nm變為788nm再變為高溫相(Pmmm)的720nm。室溫之拉曼光譜量測，發現拉曼位移峰值為105 cm-1、151 cm-1、220 cm-1與293cm-1。霍氏轉換紅外（FT-IR）光譜結果發現接近2~8μm的附近為其穿透範圍。至於I-V量測結果發現金與鎢電極材料為近似歐姆接觸;而銅則為蕭特基接觸。

We have successfully synthesized the CsGeI3 polycrystalline bulk material using heateatment method. We also growth the CsGeI3 crystal using vertical Bridgman method seedlessly, then regrowth the CsGeI3 single crystal in (2 0 0) direction using the previous crystal. The photoluminescence measurements of the CsGeI3 single crystal have been performed in various temperature and laser focusing condition. We found that CsGeI3 crystal change its phase due to the degree of the laser focusing. When the exposure ligth intensity increased, the PL peaks varied from the lower temperature phase (R3m), peak value 409nm to peak value 788nm, and then to the higher temperature phase (Pmmm), which the peak value were 728nm. There are 105cm-1、151 cm-1、220 cm-1、293 cm-1 Raman shifts have been detect in room temperature. The FT-IR results showed that CsGeI3 compound exhibited a transparent range from 2-8μm. We also found the Au and tungsten can nearly be ohmic-contact with CsGeI3, and the copper is schocky-contact with CsGeI3 crystal according our I-V measurement results.