| 摘要: | 本論文的主要目的是探討以多孔矽（porous silicon）材料製作之發光二極體（light-emitting diode）的光電特性。在相同結構的氧化後多孔矽之上，分別沈積非晶矽氫（a-Si:H）及非晶碳化矽氫（a-SiC:H）n-i-p-n薄膜以改善元件特性。沈積非晶質膜時所用的電漿助長化學氣相沈積（PECVD）系統中附有一不銹鋼濾網。用以減少電漿直接撞擊薄膜所造成的傷害，同時亦可降低薄膜表面形成不必要聚合物的機會。再者，我們亦嘗試在沈積薄膜前，事先以乾蝕刻（dry etching）的方法將多孔矽上之氧化層去除，以降低元件的發光臨界電壓。 所研製的氧化多孔矽發光二極體都有不錯的整流特性，所採用的結構及製程均可有效提升元件的發光效率及降低元件的發光臨界電壓。 In this study, the conventional plasma-enhanced chemical vapor deposition (PECVD) system with an additional stainless steel (s.s.) mesh attached to cathode was used to deposit n-i-p-n a-Si:H layers onto oxidized porous silicon to form oxidized porous silicon light-emitting diode (PS-LED). The obtained PS-LED had a higher brightness (B) and a lower threshold voltage (Vth), as compared with the PS-LED fabricated with the same PECVD system without a s.s. mesh. The improvements of opto-electronic characteristics for the PS-LEDs would be mainly due to the used s.s. mesh, which would result in a deposited film with less plasma damages. Also, n-i-p-n a-SiC:H layers were used to fabricate the PS-LED, to further improve device performances. The obtained PS-LED had the better optoelectronic characteristics, but its electroluminescence (EL) peak wavelength was red-shifted, probably due to, although the a-SiC:H layer had a higher optical band-gap but it also had a more random and hence more tail states, so the electron-hole pairs had more chance to be recombined through tail states. |
