矽離子佈植二氧化矽中雜質與奈米矽晶特性分析

Abstract

本篇論文主要研究，矽離子佈植二氧化矽 (SiO2:Si+) 經1100oC 1-3小時高溫退火下，雜質與奈米矽晶 (nc-Si) 在SiO2:Si+的特性分析與所形成的半導體特性。 多重佈植條件的SiO2:Si+，在1100oC，3小時退火過後，nc-Si和激發光源強度的微光激螢光光譜 (m-PL) 相關特性中，直徑4 nm的nc-Si在m-PL 724 nm顯現出最強的峰值強度，而藉由激發光源強度從10 mW/cm2增加到300 mW/cm2，退火1小時和退火3小時的SiO2:Si+，分別發生小於1.2 nm和11 nm的紅位移現象，近一步觀察中，在激發光300 mW/cm2持續1小時的照射下，3小時退火的SiO2:Si+亦發現2.5 nm的紅位移現象，這樣的紅位移現象我們將他歸因為光照下nc-Si光離化產生SiO2:Si+內建表面電場所引發的異常量子侷限stark effect，再藉由光照下，表面電荷的累積與壓降測量實驗，說明了nc-Si光離化產生的內建表面電場與m-PL紅位移的關係。另一方面，我們討論在含有nc-Si的SiO2:Si+基底上，金屬-半導體-金屬光偵測器 (MSM-PD) 結構中，nc-Si增強光電導的特性。在電性結果中顯示，SiO2:Si+在退火引導的漏電流與nc-Si有著非常強烈的關係，其中在含有nc-Si的Al-SiO2:Si+其接觸電阻、片電阻與特性接觸電阻率分別為9.1×108 W、 6.6×1010 W cm2與3.4×1011 W/‪。而不同的載子傳輸模型也將提出並解釋nc-Si電流-電壓的特性關係，在數值模擬的顯現中，Schottky carrier transport模型是較符合金屬與SiO2:Si+的電流傳導機制，其飽和電流(Js)為4.4 pA，近一步含有nc-Si的MSM-PD量測中，nc-Si呈現出的光電流增益為3與光電流響應為6.69 nA/W。另外，在波長的響應中，當機發光源波長為745 nm時，我們發現最強的光電流值為42.6 pA。

This thesis investigated the characteristics of defects and nanocrystallite silicon (nc-Si) in the silicon-ion-implanted dioxide (SiO2:Si+) and the semi-conducting properties of the SiO2:Si+ with 1 to 3-hrs furnace-annealing processes at 1100oC. The pumping-intensity dependency of nc-Si related micro-photoluminescence (m-PL) from the multi-recipe Si-implanted quartz is characterized. After annealing at 1100oC for three hours, the intensity of m-PL at 724 nm contributed by nc-Si with a diameter of about 4 nm is the maximum. By increasing the pumping intensity from 10 kW/cm2 to 300 kW/cm2, the m-PLs of 1-hr and 3-hr annealed Si-implanted quartz samples are red-shifted by <1.2 nm and 11 nm, respectively. The m-PL of 3hr-annealed sample further red-shifts by 2.5 nm after pumping at 300 kW/cm2 for one hour. Such a red-shift in PL is attributed to the anomalous quantum stark effect under strong illumination, which photo-ionizes the buried nc-Si and initiates an electric field beneath the surface of Si-implanted quartz. The measurement of accumulating charges and voltage drop during illumination primarily elucidate the correlation between red-shift in PL and the photo-ionized nc-Si induced surface electric-field. On the other hands, the Si-nanocrystal-enhanced photoconductivity of a metal-semiconductor-metal photodetector (MSM-PD) made on multi-recipe SiO2:Si+ substrate is reported. The result of the electrical characteristics show that the annealing-induced leakage current of the SiO2:Si+ material are strongly related to the nc-Si. The Al-SiO2:Si+ contact resistance, contact resistivity and the sheet resistance of SiO2:Si+ containing the nc-Si structure are determined as 9.1×108 W, 6.6×1010 W cm2, and 3.4×1011 W/‪, respectively. Different carrier transport models are employed to elucidate the nc-Si related current-voltage characteristics. The simulation reveals that the Schottky carrier transport predominated the carrier transport between metal–SiO2:Si+ interface. The reverse-saturation current (Js) for the SiO2:Si+ based MSM-PD is 4.4 pA. The MSM-PD exhibits photocurrent gain of 3 and responsivity of 6.69 nA/W. Wavelength dependent photoconductivity is also observed a maximum photocurrent of 42.6 pA at wavelength of 745 nm.